AC Problems/Questions

[Steeda90GT]

OK, I've been hunting down this AC problem. Here is what I have so far:

I turn the knob to "MAX AC" and the fan on "HIGH". Nothing but warm air in the cockpit. My compressor kicks on for about 10 seconds, then kicks off for 10 seconds. This is a continuous cycle.

So I decided to bypass the pressure switch (located on top of the cansiter on the passenger side firewall). Once bypassed the compressor runs continuously without interruption...however there is still warm air blowing through the vents. I purchased the switch anyways ($22 at Napa Auto Parts), install the switch and still warm air.

Then I decide to purchase R134 with gauge, hook nozzle up to DRIVER'S side hose (the one that runs on the side of the upper intake plenum). Attempt to fill, however the system doesn't seem to accept it. When the compressor kicks on for 10 seconds, the pressure seems to drop very low...almost 5psi. Then when the compressore kicks off, the pressure raises up a lot, all the way in the "Yellow Zone".

I notice that the AC tube going into the firewall is ice cold, however no cold air in the cabin.

What do you guys think?

 

[94-302-vert]

I think you have a blockage preventing air from going over your evaporator... OR.... your heater failed in the hot position and it is therefore warming the cool air....

What was the pressure reading on that port with the system off and stabilized thermally (say 15-20 minutes). Also what is the temp outside at this point in time?

Chris

 

[Steeda90GT]

What was the pressure reading on that port with the system off and stabilized thermally (say 15-20 minutes). Also what is the temp outside at this point in time?

It was about 95 degrees outside. So I should check the pressure with the engine off (after its been cooled down for 1/2 hr)?

Also should I be filling it from the passenger side or driver's side. I keep hearing from people to do it on both sides...

 

[BlownFiveLiter]

You should fill it from the low pressure (driver's) side. Dumping it in as a liquid on the high pressure side will cause damage to the valves in the compressor. If it doesn't accept the refrigerant on the low side, fill a bucket with hot water, and put the can in it. The can will heat up and force the refrigerant into the system. Do this carefully however, and keep an eye on the manifold gauge, you don't want to overfill and blow seals. Let us know how it goes, and if your compressor still keeps cycling.

 

[88GT460]

as said before, make sure that the cold/hot knob in the cabin isn't stuck on the heat side, take off the knob and make sure it is turning it

 

[94-302-vert]

Good point about heating the can.. if it is 95' out then you need the can to be warmer than that (higher pressuer) to force the refrigerat into the system if it not running as this should lower the pressure and temperatue at the low pressure (drivers side) port.

Chris

 

[Steeda90GT]

Well i tried the hot water method, still didnt work. I also tried placing the bottle on the scorching hot intake manifold for a while. I got the bottle pretty hot, still didnt work

 

[94-302-vert]

WHat is the pressure of the system with the car off and the the system stabilized?

Chris

 

[Steeda90GT]

WHat is the pressure of the system with the car off and the the system stabilized?

Chris

I believe it is around 70 psi (in the red zone)

 

[Traitor5150]

When a compessor kicks on then off very quickly it usually means the pressure is low so it kick off to avoid damage to the pump. I dont like those bottles to refill the system. I have the evac machine at My farthers shop works mutch better first it pulls a vacume in the system then hold it to check leaks then you fill it to the suggested amount about 2.00 for our cars find someone that will do this cheap and thats your best bet.

 

[94-302-vert]

If it is sitting at 70 psi and the temperature was what? This should give us an idea if they system has enough charge in it or not. It could even be over cahrged...

Did you byoass the high pressure or low pressure switch. That is the low pressure one right?

Chris

 

[Steeda90GT]

If it is sitting at 70 psi and the temperature was what? This should give us an idea if they system has enough charge in it or not. It could even be over cahrged...

Did you byoass the high pressure or low pressure switch. That is the low pressure one right?

Chris

Yes I bypassed the low pressure switch to check it. After that I purchased a new low pressure switch.

 

[94-302-vert]

I just talked to a buddy who does A/C on the side and he said that your 134a level is very low. Basically he said to hook up the can and leave it there with it running. Just make sure you put a gauge on the high side port to monitor that pressure as well. It should stay under like 300 or maybe a little more.

eventually it will catch up and start working properly.

Chris

 

[mo_dingo]

after the system is stabilized, you should see much less then 70psi. My guess is somewhere around 1 or 2atm.
Scott