95 Corolla AC Problem


#1

The AC on my 95 Toyota Corolla works perfectly in cold or cool weather. When it’s hot & humid, it works fine for about 3 - 5 minutes and then fades. If I turn off the car and let it sit for a couple of hours, it will work again, but only for 3 - 5 minutes. It will go indefinitely if I only run it for 15 seconds at a time and shut it off for about 5 minutes in between. Any ideas about what the problem might be? My car has about 163000 miles on it.


#2

When was the last time you replaced the belts on the car?
Sounds like one might be too loose, and needs to be replaced.

Also, make sure the radiator and condensor are clean, and free of any bugs and damage.

BC.


#3

This can also be an indication that you have a small leak and are leaking refrigerant. That makes your system partially full, and that will cause the conditions you describe (cool, then warm, let car sit, AC works good for some small time). You need to identify the leak and then recharge the system.


#4

Thanks for responding. The belts were replaced at 120000; car now at 162000. I will check them. Could a dirty condensor ice up on a hot humid day and cause the condensor to shut off? The AC works fine when it’s cool out. Big Question: How do I get at the condensor? It seems to be behind the firewall. Removing the glove compartment will get me to the fan/motor assembly, which I replaced in my wife’s 98 Corolla, but I don’t recall seeing the condensor.

Thanks again, WM


#5

This problem could be caused from a compressor that’s beginning to run too hot. The compressor has a thermal limit switch mounted on it. This switch cuts power to the compressor clutch if the compressor begins to get too hot. This would explain why it operates under cooler conditions and not under hotter conditions. And this is also why if you run it for short time and then turn it off it continues to operate. Because you prevent the compressor from overheating. One way to check for this is to point a thermal laser gun at the compressor as it operates to determine if the temperature of the compressor housing exceeds the thermal limit switch rating. Afterall, there is 163,000 miles on the compressor, and this is usually the life of a compressor.

Tester


#6

Thanks for responding. I never considered that, i.e. the thermal limit switch. What causes a compressor to run hot? How can I expose/access the compressor? Firewall side or glove box side?

WM


#7

condenser behind glove box? nah!

compressor behind glove box? nah!

thermal limit switch,eh! possible.(not likely.) check the drain tube.not behind the glove box.

take it to the dealer.before you hurt yourself.


#8

My experience with Toyotas is that you have either too low feon (a minor leak, as others have stated) which causes the problem of freezing up. The expansion valve will develop ice, and no longer allows the refrigerant to pass through to create the low pressure required to ‘cool’ the car. Other things to look at s the fans up front, and the condensor. If the heat can’t disapate heat, then the head pressure goes up and the compressor kicks off.
I have found that every other year or so, to havethe system evacuated, vacuumed and recharged to help keep the system free of moisture. The system will lose freon naturally, and is most noticable ater a five year mark.
The theory behind air conditioning is that the compressor puts the freon into high pressure (liquid), then is slowly release through a fixed orifice or expansion velve, which drops the pressure in the evaperator (inside the car)causing codensation (water dripping out under car) and removes the heat through the return. From there it goes to the font of the car (condensor) where it is cooled, and sent back to the compressor to be turned back into high pressure (liquid). That is a pretty basic explaination, but it is the easiest for my customers to remember. The a/c system doesn’t make the air cold, it removes the heat. Hope that helps


#9

You’ve got it wrong.

The compressor takes a low pressure gas and compresses it through the condensor which converts it from a high pressure gas to high pressure liquid. This high pressure liquid is then passed thru a metering device such as an orifice tube or expansion valve. This high pressure liquid is then converted back to a low pressure gas in the evaporator which absorbs heat from the air passing thru it and also causes moisture to condense. This low pressure gas is then passed thru the reciever/drier afterwhich it returns back to the compressor. And the cycle repeats.

Tester


#10

Dont’ be too quick to judge. Although I may not have the text book explanation, it is by the diagram. Compressor, expansion valve, evaporator, reciever/dryer, condensor, compressor.


#11

The basics.

Tester


#12

That is a really good site, but I’m staring at the Toyota Repair Manual for a 95 Corolla. I don’t want to get into an arguement. I have read some of your other post… you have knowlege. How stuff works on paper at times is different than how stuff works in reality, and I work on these things everyday…although the diagrams in the website are close, an air conditioner in a vehicle is slightly different than those at home, or in the refrigerator, etc…and they work a little different. The basic principle is the same though. Same means to and end…just a different order.
There are enough diferences to where a person certified to work on autombile A/C systems are not qualified to work on commercial/resdental systems, and vice versa.


#13

I’ve already cleaned out the drain tube that protudes through the firewall (directly opposite the glove box). I did that once before when I got a musty smell using the AC. Cleaning the tube took care of the smell, but it did nothing to impact the current problem.

WM


#14

Tester, The High side liquid line gets the receiver/drier. The low side gets a accumulator if so equipped.