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A/C doesn't work at idle Pages: 12

joe45 on Thu May 07, 2009 2:47 PM User is offline

Year: 2001
Make: cadi
Model: seville
Engine Size: 4.6
Refrigerant Type: r134a
Ambient Temp: 72
Pressure Low: 80
Pressure High: 110

To keep this short I bought a used Seville and the A/C didn’t work. I ended up replacing the compressor, accumulator, orifice tube and flushing the entire system. I recharged it with three 12oz. cans of R134a. The system holds 35oz. so since I didn’t get every last drop out of each can I have to assume that 3 cans is very close to 35oz. So why does it not work at idle?
These are the pressures I was getting.

Ambient = 72F
RPM= 800
Low =80 psi
High =110 psi
At the vent= warm air


Ambient = 72F
RPM= 1800
Low =50 psi
High =150 psi
At the vent= Cooler air

On the highway it cools fine. Nether the condenser or evaporator coil had any debris in it during the flush. The only thing I can think of is the office tube is clogged or the condenser coil needs the fins power washed.
Any thoughts?


Edited: Thu May 07, 2009 at 2:53 PM by joe45

GM Tech on Thu May 07, 2009 3:16 PM User is offline

That 50 / 150 point isn't very good either-- I would have titled your post as-- A/C does cool at all-- let alone idle..

Anyway- It acts like your orifice tube is not seated properly, did you have any trouble inserting new one-- did it "glide-in" or did you have to force it? Is it the right one? - I have seen them in backwards etc before....The idle point looks like there is NO orifice tube- seen that before too....

I'd check it out- as long as you are sure the compressor was new- BY THE WAY- what was the reason to replace OEM compressor? Bad pressures? leak? Those Mitsubishi scrolls can be tricky sometimes.

-------------------------
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......

joe45 on Thu May 07, 2009 3:31 PM User is offline

The old compressor died due to a broken motor mount which then broke off the suction line. Then to top that off the low pressure cut out switch was stuck on so the compressor was running exposed to atmosphere for god knows how long. So I replaced it with a reman which looked exactly the same as the original. Now for the orifice tube it looked the same as the one I pulled out. I got it from rock auto. It did go in like a bitch so I may have damaged that. I guess I’m going to have take it a part and look. What way should it face incase the original one was in wrong? Right now the filter side faces the high side.

GM Tech on Thu May 07, 2009 10:39 PM User is offline

Big screen on the OT is always inlet according to flow- flow is from condenser to evaporator- so I think you have it in right direction- but it may not be seated- thus allowing blowby.....

-------------------------
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......

joe45 on Fri May 08, 2009 10:28 AM User is offline

It must not be. If I remember right the orginal one was deep in the tube but the new one was such a tight fit I couldn't push it in that far. I will take it apart this weekend and have a look.

GM Tech on Fri May 08, 2009 10:40 AM User is offline

The "tabs" on the end of the OT are for the "puller" tool--that no one uses-- so the other key is that the tabs are always the last part in-- so the puller tool can grab ahold of them--I have seen mechanics actually cut these tabs off- so that the OT will fit in the wrong direction.

It's hard to "idiot-proof" things sometimes- when you're dealing with...........

I always oil the o-ring on the OT prior to insertion, and if it doesn't feel like it seated snuggly- then look for a reason why, there should be no protruding part of the OT, lay it out on top of pipe- you can see where the dimples are in the pipe- and where the depth of the o-ring seal should be-- then insert it, if it doesn't go in all the way, then you either have the wrong OT, or some other problem. Heck, if in doubt, thoroughly clean the OEM tube- and re-use it- done that before, not much can go bad on an OT!

There was a post not long ago- where the poster had put the OT in too far (or something like that) and actually broke his thermistor sensor- can't recall all the details, but that was causing the a/c trouble codes.

-------------------------
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......

Edited: Fri May 08, 2009 at 12:11 PM by GM Tech

joe45 on Mon May 11, 2009 8:27 AM User is offline

OK I pulled out the old orifice tube and replaced it with a brand new one. The old one didn’t look that bad but, it had a few small gray partials on it. I have not recharged it yet due to it only being in the 40’s this past weekend.

My question is when I begin charging the system with new freon (12oz cans) is there anyway I can tell right away the problem is fixed? I’m assuming last time I charged it my low side pressure was too high and that is why it had to rev the engine to make it take the freon in. So if my low side pressure builds to say over 50psi while charging something is still wrong?

Cussboy on Mon May 11, 2009 9:01 AM User is offline

Quote
Originally posted by: joe45
OK I pulled out the old orifice tube and replaced it with a brand new one. The old one didn’t look that bad but, it had a few small gray partials on it. I have not recharged it yet due to it only being in the 40’s this past weekend.
My question is when I begin charging the system with new freon (12oz cans) is there anyway I can tell right away the problem is fixed? I’m assuming last time I charged it my low side pressure was too high and that is why it had to rev the engine to make it take the freon in. So if my low side pressure builds to say over 50psi while charging something is still wrong?

Yours takes R134a, not "freon". "Freon" is DuPont's tradename for its R-12. Have you checked the fan(s) that blow air over the condenser? I'm assuming yours has the electric fans, if not: fan clutch.

joe45 on Mon May 11, 2009 10:34 AM User is offline

I meant R134a my bad. As far as the fans it has two and I know one works for sure because I can feel the air moving but I have not visually verified that both are functioning.

Edited: Mon May 11, 2009 at 12:45 PM by joe45

GM Tech on Mon May 11, 2009 4:40 PM User is offline

The cooler the anbient, the easier the refrigerant should flow in-- low side is lower than when it is warmer......

-------------------------
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......

joe45 on Tue May 12, 2009 8:18 AM User is offline

OK I didn't know that, but ether way I not going to have time to work on it until this weekend.

joe45 on Mon May 18, 2009 9:57 AM User is offline

OK, I do have a cooling fan problem. I started charging with my first can of r134a at 1800rpm and the low side pressure soon started to climb. When I got to my second can the psi was at 50. I removed the cooling fan relays and jumpered them on with a piece of wire. Immediately the low side pressure dropped and the system took on r134a again. My question is at 55 degrees ambient temp is the condenser coil supposed to be getting that hot? On the upper left side of the coil where the two lines enter it was so hot you couldn’t put your hand on it. After I jumpered the cooling fans and put the garden hose on it the pressure really dropped.

joe45 on Tue May 19, 2009 8:17 AM User is offline

OK a guy on the cadillac forum said my elec. cooling fans should be running any time my compressor is running. I think that will fix my problem.

Cussboy on Tue May 19, 2009 8:57 AM User is offline

Quote
Originally posted by: Cussboy Have you checked the fan(s) that blow air over the condenser? I'm assuming yours has the electric fans, if not: fan clutch.

Quote
Originally posted by: joe45
OK a guy on the cadillac forum said my elec. cooling fans should be running any time my compressor is running. I think that will fix my problem.

Yep, I agree with the guy from that forum, the fans should be running. Sounds like you're on the right track, good.



joe45 on Tue May 19, 2009 10:46 AM User is offline

I ordered the whole dual fan assembly for $120. I hope it makes it here by the weekend.

joe45 on Tue May 26, 2009 8:16 AM User is offline

OK I haven't installed the fans yet this is the readings I get with the cooling fans jumpered on low which is normal for A/C operation.

ambient temp 65
RPM 2000
Low side 45 psi
High side 110 psi

If you haven’t read the beginning of this thread I replaced the compressor with a rebuilt one off e-bay (I know that was stupid). After doing some research I found out it was rebuilt in china. So now I’m thinking the compressor might be junk again. I’m getting very frustrated with this whole deal and I’m thinking of starting all over again with a new compressor, condenser coil and accumulator. The condenser coil doesn’t leak but most of the fins are bent and full of little rocks I can not get out with a pressure washer. Suggestions?

joe45 on Mon June 08, 2009 8:45 AM User is offline

So I replaced my $160 rebuild in china compressor with a brand new $149 AC Delco one I got on eBay. Then I removed the condenser coil and power washed out the fins. Put the whole works back together with a new orifice tube and accumulator and it works! I just need to figure out why the cooling fans don't kick on with the A/C. I’m thinking it’s the A/C power module or climate controller itself because the fans kick on fine when the engine temp calls for it.

GM Tech on Mon June 08, 2009 11:03 AM User is offline

It is probably waiting on head pressure- does the system experience HPCOs (high pressure cut-outs) at idle?

Does your Caddy Forum buddy read the service manual? - it clearly states that a/c pressure must be 199 psi before cooling fans come on---see detail below.....

Cooling System Description and Operation
Cooling Fan Control
The engine cooling fan system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and the fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G104.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan s/p relay and the left cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 2 relay coil is energized, closes the relay contacts, and provides battery positive voltage on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.

The PCM commands the low-speed fans ON under the following conditions:

• The engine coolant temperature exceeds approximately 106°C (223°F).

• The transmission fluid temperature exceeds 150°C (302°F).

• The A/C pressure reaches 199 psi (1372 kPa).

The cooling fans will switch from low to OFF when the coolant temperature drops below 102°C (216°F).

The PCM commands the high-speed fans ON under the following conditions:

• The engine coolant temperature reaches 112°C (234°F).

• The transmission fluid temperature is more than 151°C (304°F).

• The A/C pressure reaches 260 psi (1792 kPa).

• Certain DTCs are set.

The cooling fans will switch from high to low, except when DTCs are set, when the coolant temperature drops below 106°C (223°F).



-------------------------
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......

joe45 on Mon June 08, 2009 2:24 PM User is offline

I did read some where in the Cadillac forums about that 199psi. I did replace that sensor also I think it was called the low pressure cut out switch. Its the one on the high side near the output of the compressor. I suppose you need a scanner to read the output of that sensor too. Since Saturday (when I replaced the compressor) its been cold here in MN for June so I haven't needed the A/C yet. I know for a fact the old compressor was not getting over 150psi on the high side so that may have been the problem because I'm not getting any codes ether.

joe45 on Mon June 08, 2009 2:37 PM User is offline

Another think I should add. When I recharged the system this time I was using the small 12oz cans. I had the brick on the gas peddle holding the RPM at 1800. I jumpered the compressor relay so it would stay running and by the time I adding the 2nd can of 134a I noticed the top left hand side of the condenser coil where the inlet and outlet are started smoking it was so hot. I then got the garden hose out and left it trickle and the condenser as I finished adding the 134a. Now I did flush the condenser coil with lacquer thinner when I had it out of the car with a small peristaltic pump and it seemed to flow freely but is this normal to get this hot? The cooling fans where not on at the time.

GM Tech on Mon June 08, 2009 2:42 PM User is offline

The sensor you are referring to is called the high side pressure transducer- a 3-wire sending unit that reports exact high side pressure to the PCM to interpret when to disactivate the compressor for low pressure, for high pressure, and for low speed cooling fan operation, and for high speed cooling fan activation..

Yes, you can read its output on the Tech II scanner, as a voltage and as a pressure in psi units. There are typically no codes set if fans are inop-- so I would say your fans are working, just you haven't tested them properly. It is always good to know the rules of the game before you test.

Some Folks believe fans come on any time a/c is requested-- but that is old school-- all W-bodies from early 90's to present wait on head pressure-- and now Caddy has followed suit--- why would you want the fan(s) on while driving down the freeway- wasting good electrical energy anyway? The fans only need to be on when head pressure is elevated-- so put in a pressure transducer and let the car decide when it needs the fan(s). Sounds like pretty good logic to me....it just fools those who listen to "old timers" - like what happened to you--

This is why it is always best to refer to the auto service manual- instead of someones hearsay--things change- yearly in some cases...you would do well to subscribe to Alldata, or Mitchell on demand if you continue to work on your own vehicle-- or better yet, buy the service manual for your car....

-------------------------
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......

GM Tech on Mon June 08, 2009 2:47 PM User is offline

You jumpered the compressor- the car did not know the a/c request (from control head) was there or it would have turned on the fans for you-- so you would have to jumper the cooling fans as well--- why not let the car decide what to do? Why jump everything-where did that idea come from?

With Caddys, the first thing you do is clear all a/c codes, then evacuate and recharge and turn on a/c- it takes over the entire process.
I guess with adding refrigerant with cans it can be tempting to jump things- like used to be done 20 years ago....

-------------------------
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......

joe45 on Mon June 08, 2009 2:57 PM User is offline

OK thanks, that makes a lot more since. I will keep a eye on it as it gets warmer out this week.

joe45 on Fri June 12, 2009 11:54 AM User is offline

Its works now! After wasting lots of time and money I found that it wasn't a unseated orifice tube bad condenser coil or faulty pressure sensor. It was the cheap rebuilt in china compressor I bought off of e-bay. DO NOT BUY A COMPRESSOR FROM THIS GUY!!

EBay seller name:
autoaccompressorsworld( 148)

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