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Correct center duct temperature? Pages: 12

barnabas1969 on Mon October 10, 2011 5:06 PM User is offline

Year: 2005
Make: Saturn
Model: VUE
Engine Size: 2.2L
Refrigerant Type: 134a
Ambient Temp: 86
Country of Origin: United States

Hi folks,

I've just completed my first automotive A/C system repair. I installed a new compressor, TXV, condenser, receiver/drier, and high-side filter.

To get the obvious questions out of the way, I'll provide the following information:

I flushed the evaporator and lines, popped them dry with filtered, dried, compressed air, then purged with dry air from SCUBA tanks for 30 minutes (SCUBA air has no moisture).

I added 7oz PAG100 oil, split among the compressor, condenser, and receiver. Torqued all the fittings to specification, and I turned the center of the compressor clutch by hand 15 revolutions clockwise. Then, I evacuated the system for an hour, and it held vacuum for 5 minutes perfectly.

The vehicle calls for 1.5 pounds of R134a. I charged it with 12 oz cans, but I used a digital scale to measure the amount dispensed. I bled the air from the yellow line on the manifold set first, and then measured the amount dispensed from each can. One and a half pounds equals 24 ounces (plus 2 for the manifold set as I've read here). So, my target was 26 ounces. I charged it with 28.4 ounces. I read somewhere that +/- 2 ounces is OK.

So, on to my question...

Unfortunately, this past weekend was an unusually cool weekend here in Florida. It was only 70F outside, so it was difficult to get a good temperature test. The pressures read 150/40 at idle speed. I didn't try 1500 RPM as I didn't have an assistant and there's no way to rev the engine from under the hood (drive by wire).

Finally, today, the outside temp is 86F. I'm at work now, so I can't put a set of gauges on it and I won't be home until after dark. I took it for a drive a little while ago and at an ambient temp of 86F, I get the following center duct temps. I'm just wondering if these are normal... it's hard for me to tell as this vehicle has had such cold air for the past couple of years that it would actually freeze the evaporator due to a stuck TXV.

With 86F ambient, I get:

43F - with fan speed on 3, recirc, highway speed
48F - with fan speed on 3, recirc, idle speed

48F - with fan speed on 3, fresh air, highway speed
55F - with fan speed on 3, fresh air, idle speed

This seems just a little warm to me, but REALLY close. I'm thinking that I need to get a look at the pressures on a day when the outside temp is 85 or so... and aim for a low-side pressure in the 32-36psig range.

What do you folks have to say?

Appreciate the feedback.




-------------------------
Brian - Melbourne, FL USA

mk378 on Mon October 10, 2011 5:25 PM User is offline

This appears to be a variable compressor system-- where the compressor prevents evaporator freezing by refusing to pump the low side below the designed setpoint. It's a popular misconception that a TXV regulates the evaporator to a specific temperature; actually it tries to get the evaporator as cold as practical given the low side pressure. You can use the same TXV for an air conditioner or a deep freezer, until the limits of the refrigerant itself are reached.

So you really need to get pressures at 1500 rpm.

Edited: Mon October 10, 2011 at 5:26 PM by mk378

GM Tech on Mon October 10, 2011 8:06 PM User is offline

Who cares about duct temp? Are you satisfied with a/c on and windows up? or do you want to open them? As long as you, the driver are happy, and can be comfortable, that is the key-- I never check duct temps, I use my hand- if it is cooling and I think the owner will be happy-- out it goes...if not, then start looking again....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

barnabas1969 on Mon October 10, 2011 11:25 PM User is offline

OK, to reply to the two posts above...

@mk378: You're the 2nd person to say something about a variable displacement compressor. However, everything I've read about my particular model is that it is a scroll compressor. Do/did they make a variable displacement SCROLL compressor (in 2005)?

Also to mk378... I'll get the pressures as soon as I have a warm day and time to do so. I'll be flying to NY in a couple of days, so I'll get to it when I can.

@GM Tech: I don't think I'd want you working on my A/C. I've had "certified" mechanics tell me that my A/C system was working perfectly... until I took his manager for a 30-minute ride in the car (that's how long it took to convince the guy that it wasn't normal for the cabin temperature to be 90 degrees on a 95 degree day after driving for 30 minutes). That was back in 1993 on a brand new car. They replaced the entire A/C system.

However, in reply... no it's not as comfortable as I would expect it to be on an 86F day. It works OK on recirc... but not on fresh air... and I wouldn't want to be sitting in that car on a 98F day in Florida when the humidity is 95%.

Additional information... I just calibrated my thermometer. It was off by 2 degrees F. So, add 2F to all my measurements above.

I'll get pressures as soon as time permits. I'm leaning toward the fact that I overcharged the system by 2 ounces or so. I would imagine that reducing the charge a little bit would result in lower low-side pressure... and therefore lower evaporator temperature.

-------------------------
Brian - Melbourne, FL USA

TRB on Mon October 10, 2011 11:35 PM User is offlineView users profile

Many variables play into a vent temp. Maximum left duct temp is listed at 61 degrees for 85 degrees ambient. Think I would prefer GMtech's method as I'm sure he would not let a vehicle loose with a 20 degree difference in ambient.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

GM Tech on Tue October 11, 2011 3:59 PM User is offline

Go ahead and drive yourself nuts....Sooo many variables contribute to duct temps like Tim said...I always shy away from customers who keep a thermometer in the center duct...they don't know if they are cold or hot without it....and can be real picky....the system can only perform as good as it is designed- compare it to other saturns of your same model....is it just as good? If cold a/c is your primary concern, then buy a car based on that and not styling or mpg...you can't make it colder than the design allows.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

NickD on Wed October 12, 2011 7:52 AM User is offline

Most common compressor used in GM cars with the 2.2L engine is the V-5 variable displacement compressor. You should know what kind of compressor you have in your vehicle. Can only say Saturn claims to be a different kind of car company, was going on the rocks in 2005, history now, so maybe they tossed in a different kind of compressor. Post a photo of your compressor, someone here will tell you what you have, why guess?

V-5 does have the characteristic to actually decrease vent temperatures has the ambient temperature increases, would be lucky to get 60*F on a 70*F day, but that sucker really kicks out cold temperatures on a 100*F day, but that is if you indeed do have a V-5, maybe someone played with your car.

46*F isn't bad at 85*F, with an average of six complete air changes in a car per minute, wife would say, its way too cold. Other factors like the hot sun beating down heating up all the duct work play a huge roll, also if you are in recir or fresh air mode. Blower speed also plays a huge factor in vent temperatures, proper way to measure vent temperatures is to close all the vents except one center located one. Is that how you measured?

I don't even fool with vent temperatures, just measured the inlet and outlet temperatures of the evaporator, should both be cold and about the same temperature. You could have problems, did you change hoses between the vacuum and charging stage? No way you can do that without letting air in the systems. And cans are worthless, have to purge between each can change with no way of measuring that. Bottom line is to get solid liquid feeding the FOT with a V-5 and be absolutely sure you haven't overcharged it..

Another characteristic of the V-5, it runs all the time, never cycles.

None of us our mind readers to what you have done or whether your vehicle was modified or not. Makes a huge difference if we could see the vehicle, that is when we know what we have. Can only go by your word, and sure sounds like you are guessing.

barnabas1969 on Sat October 15, 2011 1:45 PM User is offline

The model number on the original compressor is 2GH-190629-EA. It says right on the label that it's a scroll compressor. Nobody answered my question about whether there is such a thing as a variable displacement SCROLL compressor.

Anyway, the outside temp today is 85F. I put the gauges on it, and it's pretty much perfect... so I guess that's just the way it is. Before it failed, I was used to it being EXTREMELY cold... so cold that it would freeze the evaporator after an hour on the highway.

My gauge readings are:

Ambient temp: 85F
RPM: 1500
Doors closed, windows open, recirc mode, high fan
Low pressure: 32psi
High pressure: 220psi
Center duct temp: 55F

Those look just about perfect. It works fine on recirc on a warm day. I'll have to wait and see on a hot day. If NickD is correct about it being a variable displacement compressor, then it may just keep the same temp, even on a 95F day.

I do kinda remember that, when the car was new, the temperature of the A/C would vary... at least it seemed to... I never drove around with a thermometer in the vent though.

-------------------------
Brian - Melbourne, FL USA

Dougflas on Sat October 15, 2011 2:26 PM User is offline

If your evap would freeze after an hour's usage, you had a problem. Evaps were not supposed to freeze.

iceman2555 on Sat October 15, 2011 2:51 PM User is offlineView users profile

This vehicle should have a SCROLL compressor. It is not a variable compressor, unless someone has modified the system from the OE.
I am not a fan of small cans...scales....etc...the best method is to charge with the correct equipment. A recharge machine that meets the recharge standards for current vehicles. The machine should be able to charge to within 1/2 oz of OE spec's. From the last post...the pressures, operational conditions, temps tend to lead to a possible undercharged system. +/- 2 oz is not an acceptable margin. 2 oz undercharged and one could experience problems such as experienced. Too much and pressures/temps can affect performance. A 2 oz difference represents a charge difference of 8%. This would be an unacceptable margin for me.
It was stated that the system rec'd a new TXV...was this TXV supplied by the aftermarket or an OE unit. We have seen some issue with aftermarket TXV's not operating as they should. The gases used in the sensor bulb/line maybe different from the OE design and this can affect performance.
But like GM states...what is comfortable for you and can the system match your demands. Try this...MAX COOL...HIGH BLOWER...ENGINE AT IDLE...DOORS OPEN (ALL THE WAY). Allow the vehicle to operate for app 5-7 minutes under these conditions. Measure the ambient temp app 1 foot in front of the condenser. Measure the center vent temps. Post this info. Measure the outlet temp of the evaporator..post this info. Measure the inlet and outlet temps of the condenser. Post this info. Typically one should see a temp difference between ambient and vent of 25-30 degrees. This is a extreme operational condition for the AC system.
What type condenser was used in the replacement? Was it an exact replacement for the OE unit...same design and material? This can make a difference also.
There does not seem to be an issue with the compressor...it is pumping....the cooling efficiency is controlled by the two heat exchangers in the system...their control devices and heat removal properties. However, the system must be properly recharged....the lower recharge rates make this an imperative for proper system performance.
Also check the cabin air filter, if equipped. It may be that the air flow is diminished sufficient to not allow for proper cooling of the inlet air charge.
Unfortunately as stated by others...the vent temp maybe affected by multiple factors, hopefully we should be able to eliminate as many as possible to determine your system performance. However,the first and foremost is that the system must be properly charged. Considering your location, I live in FL also...a bit more to the south....the posted test procedure and resultant posted pressures tend to point to a possible undercharged system.

-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

barnabas1969 on Sat October 15, 2011 4:00 PM User is offline

Quote
Originally posted by: Dougflas
If your evap would freeze after an hour's usage, you had a problem. Evaps were not supposed to freeze.
Ummm... DUH!

Obviously, I had a problem. It was this way for about 2 years. I was trying to get by with it until I can afford a new car. No matter how much refrigerant was in the system, the evaporator would freeze on a long drive. I suspected that it was a stuck/clogged TXV. Some have suggested that I have a variable displacement compressor and that there must have been a problem with it which caused the suction side to pull the pressure too low.

Either way, the system needed to be fixed. Unfortunately for me, the compressor shaft seal blew before I was ready to get a new car. I have almost 200,000 miles on the car, and I don't plan to buy another one for a year or two. So... I decided to do the job myself. Even though I had to buy a few tools that I did not already own, I saved about 40-50% off the cost of having a "professional" do the job. And, now I own those tools for life and can do this again in the future, if needed, on another car.



-------------------------
Brian - Melbourne, FL USA

bohica2xo on Sat October 15, 2011 4:24 PM User is offline

There was likely nothing wrong with your OEM TXV.

The 05 to 07 VUE has a TSB that covers icing issues. There is a thermistor in a well on the TXV. That well is supposed to be filled with a specified grease for heat transfer. If the grease is missing or under-applied the sensor will let the evaporator freeze.

My 07 VUE has always had great performance. Recently on the long pull out of Fontana on the 15, I developed an icing problem. Reduced air flow, and unable to keep up with the heat in Baker. Pretty obvious. Parked the car for 20 minutes and a gallon of water hit the 115f pavement. Everything was fine for the rest of the trip - 6% humidity & 110f.

I knew right where to look the next morning. Sure enough, there was not much left there but a film. Where did it go? My best guess is they had a vendor supply something with too much solvent or light hydrocarbon. It simply evaporated. I replaced it with a big gob of heat sink compound, and put it back together. If you want the right stuff, you will need to go to the dealer.

.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

barnabas1969 on Sat October 15, 2011 4:32 PM User is offline

Quote
Originally posted by: iceman2555
This vehicle should have a SCROLL compressor. It is not a variable compressor, unless someone has modified the system from the OE.

I am not a fan of small cans...scales....etc...the best method is to charge with the correct equipment. A recharge machine that meets the recharge standards for current vehicles. The machine should be able to charge to within 1/2 oz of OE spec's. From the last post...the pressures, operational conditions, temps tend to lead to a possible undercharged system. +/- 2 oz is not an acceptable margin. 2 oz undercharged and one could experience problems such as experienced. Too much and pressures/temps can affect performance. A 2 oz difference represents a charge difference of 8%. This would be an unacceptable margin for me.

It was stated that the system rec'd a new TXV...was this TXV supplied by the aftermarket or an OE unit. We have seen some issue with aftermarket TXV's not operating as they should. The gases used in the sensor bulb/line maybe different from the OE design and this can affect performance.

But like GM states...what is comfortable for you and can the system match your demands. Try this...MAX COOL...HIGH BLOWER...ENGINE AT IDLE...DOORS OPEN (ALL THE WAY). Allow the vehicle to operate for app 5-7 minutes under these conditions. Measure the ambient temp app 1 foot in front of the condenser. Measure the center vent temps. Post this info. Measure the outlet temp of the evaporator..post this info. Measure the inlet and outlet temps of the condenser. Post this info. Typically one should see a temp difference between ambient and vent of 25-30 degrees. This is a extreme operational condition for the AC system.

What type condenser was used in the replacement? Was it an exact replacement for the OE unit...same design and material? This can make a difference also.

There does not seem to be an issue with the compressor...it is pumping....the cooling efficiency is controlled by the two heat exchangers in the system...their control devices and heat removal properties. However, the system must be properly recharged....the lower recharge rates make this an imperative for proper system performance.

Also check the cabin air filter, if equipped. It may be that the air flow is diminished sufficient to not allow for proper cooling of the inlet air charge.

Unfortunately as stated by others...the vent temp maybe affected by multiple factors, hopefully we should be able to eliminate as many as possible to determine your system performance. However,the first and foremost is that the system must be properly charged. Considering your location, I live in FL also...a bit more to the south....the posted test procedure and resultant posted pressures tend to point to a possible undercharged system.

Finally... someone who wants to answer my questions, and seems to know what he's talking about. Thank you!

First, I used small cans and a scale because I'm a DIY'er. I'm trying to save money... and I saved 40-50% compared to paying someone else to do the job. I know that I'm really close to a correct charge, but I'm a perfectionist and I'd like to get it perfect if possible, without spending a ton of money. Honestly, I'm comfortable in the car when the outside temp is 85 degrees F... but I'm concerned about next summer when the temps will be around 95F.

From the pressures I posted, what leads you to believe that the system is under-charged? It seems to me that in order to get lower evaporator temperatures, I need slightly less refrigerant in the system.

The new TXV is a Four Seasons 39308. It looks identical to the original. It is actually an "H valve" or "H block"... the whole unit is one piece... there isn't a separate bulb that attaches to the evaporator.

I'll post pressures, etc. at idle tomorrow... it's already cooling down outside right now and I'd like to do it when it's about 85F again.

I'm already seeing temps that are 25-30 degrees less than ambient now... read my first post.

I've read that doors should be open, and I've read that doors should be closed with windows open (to prevent engine heat from entering the cabin). But, I'll test it this way (with doors open) tomorrow for you. That's not a problem.

The new condenser was an original GM part... identical to the original... but sourced directly from the OEM at a significantly reduced price compared to purchasing from a dealer.

It has been a while since I changed the cabin air filter. I'll change it, but I don't think it is restricting air flow a significant amount. Also, the cabin air filter only filters fresh air... it is not involved when the system is set to "recirc".

As for measuring the outlet temp of the evaporator, and the inlet/outlet temps of the condenser... I have an infrared thermometer. I can paint those pipes flat black to get a better reading. Would this be accurate enough?

By the way, thanks for the help. As I wrote earlier, I'm satisfied with the performance of the system when the ambient temp is 85 degrees or so, but I'm concerned about what is going to happen next summer when it will be 95 or more.

Thank you.

-------------------------
Brian - Melbourne, FL USA

barnabas1969 on Sat October 15, 2011 4:52 PM User is offline

Quote
Originally posted by: bohica2xo
There was likely nothing wrong with your OEM TXV.



The 05 to 07 VUE has a TSB that covers icing issues. There is a thermistor in a well on the TXV. That well is supposed to be filled with a specified grease for heat transfer. If the grease is missing or under-applied the sensor will let the evaporator freeze.



My 07 VUE has always had great performance. Recently on the long pull out of Fontana on the 15, I developed an icing problem. Reduced air flow, and unable to keep up with the heat in Baker. Pretty obvious. Parked the car for 20 minutes and a gallon of water hit the 115f pavement. Everything was fine for the rest of the trip - 6% humidity & 110f.



I knew right where to look the next morning. Sure enough, there was not much left there but a film. Where did it go? My best guess is they had a vendor supply something with too much solvent or light hydrocarbon. It simply evaporated. I replaced it with a big gob of heat sink compound, and put it back together. If you want the right stuff, you will need to go to the dealer.



.
I read about the TSB. My thermistor is screwed to the inlet pipe of the evaporator... right after the TXV, so I don't know what you mean about it being in a well. No matter what I did with the refrigerant charge (before the compressor failed), I could not get it to stop freezing. If I charged the system enough to bring the low pressure above freezing, the high pressure was so high that the high-limit switch would shut off the compressor.

If I was having that issue (with the thermistor), I would expect to still have freezing problems after replacing the compressor, TXV, and condenser. With the way my system is preforming now, it is nowhere near freezing... which means one of two things: A) it's working as designed, or B) it is under or over-charged.

I do have to say that I could never get my pressures anywhere near normal before I replaced all those components, so there was certainly something wrong with the TXV or the compressor. However, if I find that it is under or over-charged now... and it starts freezing after I get the pressures correct... then I'll definitely be looking at that thermistor.



-------------------------
Brian - Melbourne, FL USA

Edited: Sat October 15, 2011 at 4:59 PM by barnabas1969

bohica2xo on Sat October 15, 2011 7:16 PM User is offline

"I read about the TSB. My thermistor is screwed to the inlet pipe of the evaporator... right after the TXV, so I don't know what you mean about it being in a well. No matter what I did with the refrigerant charge (before the compressor failed), I could not get it to stop freezing. If I charged the system enough to bring the low pressure above freezing, the high pressure was so high that the high-limit switch would shut off the compressor. "

Again. You are working on the wrong part of the system Obviously you were diddling the charge levels before the compressor seal failed. And, since you were ignoring the thermistor's function you had no luck.

The system should be capable of freezing the evaporator by design. The thermistor is there to prevent the formation of ice on the evaporator. Either you have a bad thermistor, or it is not properly coupled to the suction line. Only two reasons for the evaporator to ice over if the cabin fan is running.

Charge levels are not adjusted to prevent freezing. The system needs excess capacity for rapid cool down. Once the heat load drops, it is the function of some other part of the system to prevent ice formation. In this case the thermistor.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

barnabas1969 on Sun October 16, 2011 11:33 AM User is offline

@bohica2xo: OK, as I said... if I find, with the help of the folks here, that the pressures are incorrect, I will adjust them. If it starts freezing after getting the charge correct, then I'll look at the thermistor. I understand what you're saying... the thermistor should have detected the freezing condition and shut off the compressor before the evaporator froze. I get it... I'm not a dummy. I like your idea of using heat sink compound.

I also like your name... pretty funny. Back when I worked as an electronics technician for a semiconductor manufacturer, we had to form "teams"... and each team had to pick a name. One team picked the name "The Bohica's". It took senior management two years to find out what it meant.

If I choose to take it to an A/C shop to have it charged with a charging machine, how much should I expect it to cost me for a shop to recover, evacuate, and re-charge the system?

-------------------------
Brian - Melbourne, FL USA

TRB on Sun October 16, 2011 9:09 PM User is offlineView users profile

.74 hr labor plus refrigerant.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

barnabas1969 on Sat October 22, 2011 1:25 PM User is offline

@TRB: I'm guessing that the hourly rate is around $150/hr? So, that would be around $111 for labor, plus around $30 for refrigerant? Hmmm... not sure I'd want to do that. It works well enough now.
,
@bohica2xo: I will go ahead and remove the thermistor and re-install it with some heat sink compound. I was driving yesterday with the air on. It was about 70F outside, but it was a little warm in the car because it was a sunny day... and the center duct temp dropped to 27F!!! The freezing problem was definitely a problem with the low evaporator temp sensor... or possibly the BCM (there's a TSB on that too). I'd really like to fix that problem. I'll test the resistance of the thermistor also... does anyone know the correct values vs. temperature?

@iceman2555: I tested the pressures a few days ago when it was 85F outside. They were 32/220, with doors open, high fan, 1500RPM, 55F center duct temp... exactly like what I saw with the doors closed and windows open.

I was asking a serious question... what makes you think the system is under-charged? The high pressure is exactly where it should be and the low pressure is a little too high... so, based on what I know, this seems to suggest an over-charged system. What am I missing? I really appreciate the questions you posed, and the information you provided. So far, you and bohica2xo have been very helpful and seem to be knowledgeable. I appreciate the help.

-------------------------
Brian - Melbourne, FL USA

TRB on Sat October 22, 2011 5:09 PM User is offlineView users profile

We charge $70.00 right now.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

barnabas1969 on Sun October 23, 2011 2:28 PM User is offline

I pulled the thermistor. I see what you mean by it being in a well now. There is grease on it, but I can't tell if the well is full. I'm going to fill it with heat sink compound (the kind for a CPU that comes in a syringe. I measured it with an ohm meter. It measured 52K ohms at 78F. Is this normal?

-------------------------
Brian - Melbourne, FL USA

HECAT on Mon October 24, 2011 10:17 AM User is offline

Brian, I have been following this post and want to share a thought. Pressures are a measurement of system performance and are not a measure of system charge. Charge is measured in by weight. Trying to add or remove refrigerant to obtain optimum pressures is (as others have pointed out) dead wrong.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

barnabas1969 on Thu October 27, 2011 4:51 PM User is offline

First, I want to say that adding the heat sink compound definitely worked to prevent freezing. I drove the car recently on a cool evening (70F) and ran the A/C on low fan speed. The duct temp would bounce around between 35-38F, instead of dropping to 27F as it had before. So, thanks for the advice. I had read that there was a TSB about a possible BCM calibration, but did not know about the problem with the thermal grease on the sensor. That did the trick. I wish I had known about it a couple of years ago.

Second, I understand what HECAT is saying. I read a post somewhere on this site (I think it was posted by HECAT) that says that a charge within +/- 2oz is OK. I also read a post (I think by HECAT again), that said to add 2oz to the specified charge for the vehicle to account for the gauge/manifold set. So, since my system requires 24oz of refrigerant, my target was 26oz (based on the posts I read here).

I charged with 12oz cans and a digital scale that has a resolution of 0.1oz and an accuracy of +/- 2%. The reason I went two ounces over was because I was having to immerse the can in hot water to get the refrigerant to come out (it was a cool day), and I over-shot the 26 ounce mark by 2.4oz while warming the can (it went a lot faster than expected).

The purpose of my questions here is just to be sure it's going to work OK when the weather gets hot again. It's working fine on an 85F day now, but I just want to be sure it will be OK on a hot day in the upper 90's.

I may just wait until the summer before I decide to do anything (or nothing).

-------------------------
Brian - Melbourne, FL USA

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