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Need some help with my cars A/C

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Chicken Patty

15+ Year Contributor
1,446
17
Jun 26, 2007
Miami, Florida
Recently I had a refrigerant leak on my car. The shop I took it to diagnosed it was the Compressor. So compressor was replaced along with the dryer and the a/c was kicking cold! However two days later it stopped working. I took it back, refrigerant was lost again this time one of the lines was leaking, you can see the UV reactive refrigerant they used by where it was leaking. So today I went to pick it up and it was cooling perfectly fine again. half way home the car starts to feel like it gains power, then loses power and so on. Felt like if the compressor was kicking in and out. To confirm that the a/c starts to blow slightly warmer.

So now at this point I have observed that the a/c only cools correctly and the car drives fine for the first part of my drive. once it has been a few minutes it starts to do the same. I'm assuming something is causing the the high pressure side to be too high thus causing the compressor to act like it does? If that was the case, what can it be? Condenser? I do have a FMIC, but for about two years already, the a/c just started giving these issues about a month or two ago at the most. Any idea guys? Thanks.
 
Stock fans? Where you live is hard on coolant systems.
I would start working on your own car, you will save a LOT in the long run. If you still have your stock fans and radiator, I suggest getting an aluminum rad as well as a pusher fan on a thermal switch.
That should take care of your airflow issues no problem.

Your getting warm/cold air because you have a severe restriction in airflow from the FMIC(assumption).
The pusher fan should remedy your issue as well as any heatsoak that may be causing your warm AC issues.

edit, you said you took it back because it was leaking, I assumed they fixed the leak?
 
Should be fairly straight forward. Buy a can of 134a with UV dye, and check for leaks-If you dont find any, Id bet your fans arent operating properly. However, the only reason for the compressor to kick on and off would be inadequate pressure, or perhaps a faulty high side pressure sensor.
 
Thanks for the replies guys, but the fans all both operating properly, the leaks have been fixed. THe car has enough refrigerant. I have had a FMIC for about two years now and never had this problem, why would I have it now? Any thoughts?
 
First off put the high and low side gauges on it and see what they are reading. Then go from there.
 

THank you, but if this was to be the problem, how do I get it if it is no longer made?

First off put the high and low side gauges on it and see what they are reading. Then go from there.

At the shop on idle low was about 35-40 and high was 225-280. When revved the low obviously dropped and the high got just a hair over 300, however that is just standing there revving it. Once you are in the streets and you have more load there is more heat been generated. So I dont know if while driving it for about 10 minutes the high is getting too high and thats why the compressor starts to kick in and out.

I drove it again today and it cools for about five minutes, then u feel the difference and it starts to kick in and out, compressor clutch engages and disengages constantly.
 
They might have overcharged it, or the condensor is full of debris, or just too much heat from the intercooler causing the high side to spike. Once it gets to high, it will kick the A/C off. Did they replace the expansion valve when they did the compressor?
 
you know I was about to say that. I just came from a buddies house and we noticed that when the car has the a/c on the hotside gets extremely hot and the cold side does not even start to sweat. His stepdad who is an A/C mechanic told me to change the expansion valve.

Anybody know how to replace it? i tried searching online and found nothing, it should be located by the firewall correct?
 
It takes 3.9 hours to replace the expansion valve. It is attached to the evaporator which is hidden in the dash on the right side behind the glove box.

If the compressor was just leaking and didn't grenade, then it might be ok.

After the A/C warms up and stops working like it should, try parking the car and letting it idle with the A/C on and see if it starts to cool again. Just strange that it works for a few minutes then stops.

One other thing. You said the fans work, but do they both work on high? You can test them by running the car in park until it warms up enough to kick the fans on. Then while the fans are running, turn the A/C on. You should notice a difference in fan speed after a few minutes with the A/C running.
 
THank you, but if this was to be the problem, how do I get it if it is no longer made?



At the shop on idle low was about 35-40 and high was 225-280. When revved the low obviously dropped and the high got just a hair over 300, however that is just standing there revving it. Once you are in the streets and you have more load there is more heat been generated. So I dont know if while driving it for about 10 minutes the high is getting too high and thats why the compressor starts to kick in and out.

I drove it again today and it cools for about five minutes, then u feel the difference and it starts to kick in and out, compressor clutch engages and disengages constantly.

Its low on freon. It should be about 45-50 on low side 350-400 on high. If the low side falls below 35 it will kick the compressor off. If you had a blockage the high side would be like 500 or more, but it is normal. Also if the fans were not working the high side would be up.
 
350-400 psi? That is too high! If the fans can't keep the high side at 250-300 while at an idle, then you have problems. His pressures are where they should be. More freon would make the problem worse.
 
I tend to disagree somewhat. I have a 07 Chevy Tahoe that reads about 370 on the high and it is the factory air never been touched, works great. I like to keep my other vehicles at 45 on the low, which usually puts the high right at 350. I never had a problem. I also charged my gst with exactly the amount of freon listed on the firewall. Which I believe is 32oz. It also put my gauges at 45 for low 350 for high.
 
^yikes, you better hope its not the A/c control unit. It took me two years to find one..right after my compressor seized from inactivity! :rolleyes:
 
Its low on freon. It should be about 45-50 on low side 350-400 on high. If the low side falls below 35 it will kick the compressor off. If you had a blockage the high side would be like 500 or more, but it is normal. Also if the fans were not working the high side would be up.



350-400 psi? That is too high! If the fans can't keep the high side at 250-300 while at an idle, then you have problems. His pressures are where they should be. More freon would make the problem worse.

Yeah at 350-400 which is what it is getting to when it is revved and driven, you can't touch the high side, it'll burn. The cold side is not even sweating.



Well I took it to the shop again, they checked it, no leaks.. still has about 35psi of freon. They watered the condenser and the high side goes to abou 150psi which is much better and the car will start to cool.

I think it is either the condenser going bad, or I need to add slimfans in front of it. What do you guys say. Shop says its lack of airflow to condenser, but two years with a FMIC and never had that problem :(
 
I really do believe it is lack of air. Are you noticing a difference in fan speed?

One other thing. Crusing down the highway (not boosting) does the A/C start to cool again?
 
I really do believe it is lack of air. Are you noticing a difference in fan speed?

One other thing. Crusing down the highway (not boosting) does the A/C start to cool again?

naw, once the engine temp starts to rise towards operating temp it stops, guess its just not getting much air period.
 
Is the condensor full of dirt. I used to live in South GA and my a/c stopped working in my old trans am. It would work when I had the water hose on the condensor that was it. I pulled the condensor out and it was full of grass seeds and dirt. Sprayed it out with a pressure washer to fix.
 
have you thought that maybe the compressor they put in could be bad. it sounds like the A/C clutch is going in and out. they have a clutch built into the A/C. have you checked to make sure the wires are plugged in tight and not just kind of hanging there.

maybe im wrong but i have never seen a car where the radiator fans affect how cold the A/C blows.
 
have you thought that maybe the compressor they put in could be bad. it sounds like the A/C clutch is going in and out. they have a clutch built into the A/C. have you checked to make sure the wires are plugged in tight and not just kind of hanging there.

maybe im wrong but i have never seen a car where the radiator fans affect how cold the A/C blows.

The fans are there to keep the head pressure down at idle, without that the a/c kicks off. The fan turns on with the a/c in any car.
 
The shop should have replaced the expansion valve together with the drier. That's SOP whenever you replace your compressor. A lot of the parts stores require you to do that or else they won't honor the warranty in case something happens to the compressor.
 
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