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My First Post - Really Interesting Problem

Alphacarina on Thu June 24, 2010 4:06 PM User is offline

Year: 2002
Make: Mazda
Model: Protege 5
Engine Size: 2.0
Refrigerant Type: R-134A
Ambient Temp: 90
Pressure Low: 45
Pressure High: Unk
Country of Origin: United States

2002 Mazda Protege 5 - After 110,000 trouble-free miles, my A/C recently began acting up. The green light in the A/C switch on the dash began flickering oddly - No particular pattern to it . . . . sometimes it flickers on and off as fast as you can blink your eyes, other times it shuts off completely for 2 or 3 seconds or even longer - Occasionally, it's off for half a minute or two before it comes back on

When the green light is off, so is the compressor clutch and both of the radiator fans. When the light flickers like crazy, so do they

Seemed like a possible issue with the relay which engages the clutch to me, so I did some poking around and found that there are three identical relays . . . . one for the A/C, one each for the headlights and tail lights, so I swapped the A/C and headlight relays - Nothing changed. I pulled out the clutch relay and jumpered across the socket with a paperclip. With the engine idling, about 15 seconds or so later the overpressure vent on the back of the compressor blew and I had a huge freon and oil cloud blowing out from under the hood for about 15 seconds - The wife (who had her head under the hood at the time) commented 'You blew it up' and went inside to change her drawers

I recharged it with a 15 ounce can of freon which also contained 3 ounces of oil - 45 psi low side pressure on a 90 degree day. Seemed to work OK for a day or two, but it's pretty much back to doing the same thing it was before. It's as cold as ever when it's running, no problem there but when the light begins going out (especially for longer periods) it begins blowing pretty warm

One last clue I discovered just this afternoon which may be the 'key' to the whole puzzle - We always run the blower fan on position 2 because of course the air coming out is colder when you force less air through the evaporator . . . . and it's quieter inside the car. Can't remember the last time we used anything other than 2 on the fan switch. The system cycles (somehow) as needed to prevent freezing up the evaporator . . . . the green light never goes out and you never hear the clutch kicking in or out, nor do the two radiator fans ever quit blowing - You experts will know what it's doing (bypassing?) to prevent freezing the evap without disengaging the clutch, but I haven't a clue - In my old 240Z under the same conditions, the clutch just cycled in and out

Anyway . . . . today I find that if I run the fan on position 3, the system works perfectly all the time, hour after hour - The green light on the dash never flickers. The air coming out isn't quite as cold as if we had it on 2 like we normally do, but it cools the car quite effectively . . . . I assume it's working fine because the system no longer needs to 'cycle' like it does when the fan is blowing slower

So - What's not cycling properly and what do I need to do to fix it? I appreciate all comments because (as usual) I'm still (re)learning half the stuff I *thought* I already knew!

Don

mk378 on Thu June 24, 2010 4:29 PM User is offline

Probably just the fan switch, if it is truly mechanical manual controls. Up to the early 90s practically all Japanese cars were built with an extra circuit in the fan switch that closes in any position but off, that circuit then passes on to the A/C button.

It is complicated to properly recover from blowing it up, really you should remove all refrigerant and oil then recharge both to factory specifications. At least check that the relief valve is not leaking, they don't always reseal fully.

Edited: Thu June 24, 2010 at 4:30 PM by mk378

Alphacarina on Thu June 24, 2010 4:47 PM User is offline

I doubt it's the fan switch

Normally, the little green light is always on . . . . never goes off. Now, when running on position 2 it flickers off and on to keep the high side pressures under control - When I shorted across the relay (which forced the clutch to be on all the time) it promptly blew the high side pressure vent. It would do it again now if the green light wasn't going off and on. Running the fan switch on position 3 keeps the evap from freezing up (my theory at least) and it works perfectly

As to the recharge - It still worked OK after the blow-up. I ran it that way for a week or so (no flickering of the light) but it didn't blow as cold as it did when the system was full of freon, so I added the can. No signs now that it's undercharged and it works perfectly . . . . so long as you're not using position 2 which forces it to 'cycle' . . . . which it seems it can't do any longer

What usually happens in a modern (2002) Japanese system to prevent the evap from freezing up? The clutch never disengages (which is why I thought I was safe jumpering the relay) but somehow the system bypasses to reduce the cooling efficiency when it doesn't need max cool . . . . or at least it used to

Don

Dougflas on Thu June 24, 2010 5:17 PM User is offline

If you want to get at the root of your problem, you need to see the high side pressure. If you don't have gauges, rent, borrow, or steal (kidding on that one) a set. Auto Zone has them for rent or loan. Get a schematic for your system. You can get a complete cd for your vehicle for about $25..

GM Tech on Thu June 24, 2010 6:16 PM User is offline

Sounds exactly like the Chevy Malibus and the Olds Intrigues ---a/c control is energized through the fan switch which has a master "off" position-- hence two brushes make contact as the fan switch rotates through the various speeds- since you always use fan speed two-- the brushes have been arcing in fan speed two position- when you rotate to position three- they have fresh copper to contact- so they make better connection- and run the a/c circuit. Pretty simple-just pull out the blower motor selector switch and clean and polish the brushes and their respected wiper board- use a pencil eraser-- and never see that green light flicker again----BTW stay out of the relay-- it is not the problem....control heads do not flicker just because the relay is commanded on or off.....

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

Alphacarina on Thu June 24, 2010 7:22 PM User is offline

Quote
Originally posted by: GM Tech
Sounds exactly like the Chevy Malibus and the Olds Intrigues ---a/c control is energized through the fan switch which has a master "off" position-- hence two brushes make contact as the fan switch rotates through the various speeds- since you always use fan speed two-- the brushes have been arcing in fan speed two position- when you rotate to position three- they have fresh copper to contact- so they make better connection- and run the a/c circuit. Pretty simple-just pull out the blower motor selector switch and clean and polish the brushes and their respected wiper board- use a pencil eraser-- and never see that green light flicker again----BTW stay out of the relay-- it is not the problem....control heads do not flicker just because the relay is commanded on or off.....
Yes. I'm sure that's how it gets the voltage to control the clutch and the radiator fans - Through the heater fan switch

But . . . . . back to my original problem - If I short out the relay which energizes the clutch and fans the system overpressure valve releases and I lose the coolant. Pretty obvious that the green light is flickering on and off to prevent an overpressure condition . . . . likely it's the high side overpressure sensor which is causing my flickering light - If I had gauges on it I'm sure the high side pressure would be abnormally high when the light begins to flicker

What I'm really interested to know is - How do modern Japanese systems regulate themselves whenj you don't need 'max cool'?? My old Japanese car did it by controlling the compressor clutch. This system does something different because the clutch and the radiator fans stay on *all the time* even when you don't need much cooling

Agreed that it would be nice to be able to monitor the high side pressures . . . . but this problem began on an 8 year old car with 110,000 miles on it which has never had the A/C serviced in any way therefore it couldn't have been overcharged, but it did blow the overpressure valve when I forced the clutch to run all the time . . . . like it always does when the system is operating 'normally'. It seems I have high side pressures which are too high when I run the fan on position 2 . . . . but I don't when I run the fan on position 3 because everything operates normally then

Appreciate all the replies

Don



Edited: Thu June 24, 2010 at 7:24 PM by Alphacarina

Cussboy on Thu June 24, 2010 8:12 PM User is offline

Quote
Originally posted by: Alphacarina
Quote

It seems I have high side pressures which are too high when I run the fan on position 2 . . . . but I don't when I run the fan on position 3 because everything operates normally then.
Don

It sounds like the condenser cooling fan doesn't operate either, at fan setting #2; so if you jumpered the AC clutch then, there's no way to cool the condenser, and it overpressures.

When you have the fan speed as something different like #3, then the condenser cooling fan comes on like it should, and system behaves.




Edited: Thu June 24, 2010 at 8:20 PM by Cussboy

GM Tech on Thu June 24, 2010 8:32 PM User is offline

Jumping the a/c compressor relay will never energize the fans- they should have their own relays--when you put 12volts to the pump- it creates head pressure and the fans are not on to keep the pressure down-- the high pressure cut-out switch cannot do its job either- because it would normally turn off the relay that you have decided to run full time- that is why you are spewing out refrigerant- why not let the system work as designed and fix the input problem-- the control head is an input into the ecm- and if it is blinking at a random pace- it is called "intermittent" and needs to be fixed-- there is no feedback to the control head that tells it of an overpressure condition-- the overpressure condition is information fed to the ecm that can't do its job because you have decided to jumper the relay. Quit jumpering the relay.

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

Alphacarina on Thu June 24, 2010 10:22 PM User is offline

Quote
Originally posted by: GM Tech
Jumping the a/c compressor relay will never energize the fans- they should have their own relays--when you put 12volts to the pump- it creates head pressure and the fans are not on to keep the pressure down-- the high pressure cut-out switch cannot do its job either- because it would normally turn off the relay that you have decided to run full time- that is why you are spewing out refrigerant- why not let the system work as designed and fix the input problem-- the control head is an input into the ecm- and if it is blinking at a random pace- it is called "intermittent" and needs to be fixed-- there is no feedback to the control head that tells it of an overpressure condition-- the overpressure condition is information fed to the ecm that can't do its job because you have decided to jumper the relay. Quit jumpering the relay.
I'm sure that's all true - I only jumpered the relay once for about 15 seconds . . . . that was all it took to dump the freon

The relay I jumpered is probably *not* specifically the pump clutch relay - It's just one of several relays in the underhood fuse block and it happens to be the only one labeled 'A/C'

It's (evidently) just the relay that the 12 volts from the interior fan switch energizes - I found the relay by putting my finger on it while the green light was going crazy . . . . so was that relay and so were the fans and compresser - You could feel it with your finger on it. It energizes other relays for the fan clutch and each of the radiator fans because jumpering that one relay turns on all 3 - Both of the rad fans and the comp clutch. I have never had the comp clutch energized without both of the rad fans also running. My overpressure situation has nothing to do with the condenser overheating . . . . . I tested that by spraying water on the condenser with the heater fan set on 2 and it still cuts out. It doesn't cut out running on 3 even with the car sitting still for an extended period. I initially suspected that one or both of the rad fans must be bad . . . . because my symptoms are exactly what you would expect to find if the condenser were overheating - Wish it had turned out to be that simple. My son's Cavalier A/C would work fine on the freeway but not around town . . . . it was a bad condenser fan and at only 65,000 miles

From what you say, I must have an ECM output which shuts down that relay which disables both the comp clutch and the condenser fans when high pressures are detected - I'll see if I can find that wire and check it . . . . but it still doesn't address the root cause of the high pressure, which is not lack of airflow through the condenser . . . . this problem occurs at 70 mph down the freeway if I use position 1 or 2 but doesn't happen even with an extended stop if I use position 3 or 4

I'll see if I can get a set of gauges on it and watch what the pressures are while I change the heater fan switch from 2 (where the system doesn't work properly) to 3 where everything works fine

The system is working as designed now with no problems at all . . . . so long as I don't use position 1 or position 2 on the heater fan - So long as I have MORE AIR blowing through the evaporater, all's well. If I never find or fix the problem, I'll still have cold air with the system operating normally . . . . I'll just have to get used to using position 3 or higher

I would just like to correct my problem (whatever it is) so that I can run it on 1 or 2 and not be blowing so much air around inside the car

I told you guys it was 'an interesting problem'

Don

P.S. - I'd *still* like an explanation of how the system regulates itself to prevent the evap freezing up when there's little airflow going though it, since the compressor continues to run constantly . . . . it must be somehow bypassing freon around the evap . . . . no??



Edited: Thu June 24, 2010 at 10:49 PM by Alphacarina

mk378 on Thu June 24, 2010 11:38 PM User is offline

The problem is at the control panel. Clean or replace the fan switch. It really is that simple.

Quit jumping the relays! If you force the compressor on and the condenser fan is not on, an overpressure will develop in a very short time. If the system is working as designed (no jumpers), failure of the condenser fan will just cause the compressor to shut down before the relief valve opens.

Alphacarina on Fri June 25, 2010 11:07 PM User is offline

Quote
Originally posted by: mk378 Quit jumping the relays! If you force the compressor on and the condenser fan is not on, an overpressure will develop in a very short time. If the system is working as designed (no jumpers), failure of the condenser fan will just cause the compressor to shut down before the relief valve opens.Yup . . . . that's why the green light is flickering - To keep the system from overpressurizing BUT there is nothing wrong with either condenser fan . . . . . both are running anytime the compresser is, jumper or no jumper

I give up. It does little good to type anything here . . . . nobody seems to read any of it before they reply

I've only made 5 posts - In 4 of them I've plainly stated that I have never had the compresser clutch engaged without both radiator fans running . . . . Even saying so in BOLD doesn't seem to get anyone's attention

The relay I jumpered that one time just simulated the green light being constantly on, which is it's normal condition - Clutch engaged and both radiator fans running . . . . and the system overpressurized in 15 seconds which is why replacing the damned heater fan switch wouldn't accomplish anything - If the green light is on constantly (it's normal condition) with the amount of air flowing through the evap that fan position 1 or 2 provides, the system overpressurizes, plain and simple. If I have more air moving through the evap (position 3 or 4) everything operates as normal

I'll work it out and solve it by myself . . . . I may even come back here and tell you all what it actually was . . . . but it definitely has nothing to do with THE CONDENSER FANS - They're both running just fine . . . . oh, and they have always been, even with the jumper(briefly) in place

Don



Edited: Fri June 25, 2010 at 11:13 PM by Alphacarina

ACProf on Fri June 25, 2010 11:26 PM User is offline

Actually, if YOU go back and read all the posts you'll find out that mk378 TOLD you where the problem is (along with several others). You just refuse to accept their advice and want them to give you advice that fits with what YOU think is wrong with the system.

My advice: GO FOR IT! Do what you will. Its your system and your money.

bohica2xo on Sat June 26, 2010 3:03 AM User is offline

Without a high pressure reading you have no idea what is going on. You can't claim an overpressure event based on a guess.

After blowing the HPRV with the jumper wire stunt, you have no idea how much oil & refrigerant is in the system.

You are not really sure what relay you actually jumpered to produce this disaster.

You have no idea how the system works, but because you owned a 25 year old japanese car from another maker - you believe it should work the same way.


You really don't know much. But you think you know more than the people on this board earning a living fixing MVAC. Good luck with your car.

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.

mepatten on Fri August 07, 2015 4:50 PM User is offline

My 2002 protege5 is giving me issues, I put a can of R12 in till the gauge reached 30psi. Then started the car turned the A/C on and the blower on max and emptied the rest of the 6 oz can in. Initial reading when I hooked the gauges on was 0 psi. Now I would expect the clutch to engage but hasnt thus far. Last night i seen a post that if the high side has no pressure the clutch may not engage and to bypass it for a few minutes to pressurize the high side. So I have done that, my readings now are 40- 45 psi with the clutch engaged and 70- 75 psi when its stopped. The problem I still have is when i reconnect the harness and remove the bypass, the clutch still will not engage. thoughts?

mk378 on Fri August 07, 2015 5:47 PM User is offline

You should start a new thread.

Upon finding a system at zero pressure, that means there is a major leak and the first step is to find the leak. Merely recharging is futile because it will leak out again.

Did you really put in R12? A 2002 car will have R134a. Using R12 will cause damage.

mepatten on Fri August 07, 2015 7:37 PM User is offline

Quote
Originally posted by: mk378

Did you really put in R12? A 2002 car will have R134a. Using R12 will cause damage.

I put Red Tek 12a which is advertised as compatible for 12 and 134a systems

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