1991 4runner, 3.4 swap. I have been battling the A/C system forever now. First it was leak after leak. I have all the leaks fixed. Vacuumed the system, charged, etc. The drier, condenser fan,and the expansion valve are brand new. Now, when I turn the A/C on, the compressor comes on, everything works, except for the air is only somewhat cold. When driving, it gets down to about 60-65* and up to about 85* if sitting still. (Its 100+ here so it is definitely somewhat compressing, but not near what it should.) I dont understand, the charge is correct, the components are working as they should, any ideas??

 

Use the 3.4 AC amplifier?

:wabbit2:

 

No, I kept the 3.0 one according to the recent thread, ran a couple of wires for it. The compressor and everything works. Would the amplifier cause it to not blow as cold?

 

Amplifier controls when the compressor comes on and goes off.

Never used a 3.0 one always swapped to 3.4 and never had any issues.

:wabbit2:

 

If everything is correct, make sure your compressor clutch isn't disengaging at idle. If it is, check the little knob on the A/C amplifier. I learned that the hard way.

 

Yea, the compressor stays on at idle. I adjusted the rpm cutoff to stay on, and it stays on most of the time, but its just not cooling as well as it should.

 

What were your low side and high side pressures?

 

my low side is right about 35ish, unfortunately the gauges I have dont fit the high side for r-12, and I cant find an adapter anywhere for it. I guess there where a couple different size fitting for high-sides for r-12 from what I have read.

 

What I did was used r134 gauges and r12-to-r134 conversion "nipples". If you don't want to leave those nipples on, make sure you clean the red stuff off first. That red stuff is threadlocker.

If you don't know your high side pressure, it will be impossible to diagnose what the problem could be. You need the high side pressure to judge the health of your compressor.

Insert a thermometer into your center vents and turn on your A/C for at least 15 minutes with RECIRCULATE on with air coming out just the vents. Close your windows. Make sure you have airflow at the front of your vehicle. Use a large fan. Your low side pressure should be just below your vent temperature, plus or minus 2 to 5 degrees.

 

Ok, I will have to get correct hose for the high side so I can watch both pressures than. Ill try to do it after work and post the results on this thread. Something is wrong, I just dont know what since its properly charged and the compressor is working.

 

Never know... maybe you still have a small leak somewhere. Did you inject some dye when you charged it?

 

Let us know how this turns out. You won't be the last one with this problem. Hey, summer's almost over anyhow...

 

Ok, got a proper high side fitting. She is reading about 35 psi on the low side, right about 225 on the high. Which IIRC, is right about where it should be right? If thats the case, why isnt it blowing cold??

 

I just had a cray idea. Maybe your mixing valve is partly or mostly open? Open the hood and make sure.

 

Is this only happening at idle? if so, then your aren't getting enough air moving through your front end to the condensor to cool the gases.

 

Apparently happens all the time.

 

I thought the 4runners had a electric fan at the front for the a/c. But that may be the auto's only.

 

Sounds okay.

Now, back to basics.

1) How long did you evacuate the system?
2) How much oil did you add to the system?

Oh yeah ... also, check your valve that goes to your heater core. Is it stuck open? That will do it.

 

Sorry guys, still been working on it. As for the mixing valve, are you talking about the one in the heater lines on the back of the motor?

I evacuated the system again, let vacuum for a full hour, and recharged. My pressures again are within range, but it still wont blow below 75*. The condensor fan is working btw.

 

Yes, that would be the valve I'm talking about. Make sure it's not stuck open.

Other things to check:

Touch the low pressure and high pressure lines right before it enters the firewall. The temperature difference of the two lines should be very great. That is, the high pressure line should be hot to the touch and the low pressure line should be pretty much freezing. If that is the case, then the problem is not in your A/C system. If they are pretty close in temperature, then the problem is in your A/C system.

Also, get a spray bottle of water and spray it on the condenser. Does it lower the vent temperature? If so, you have too much debris caught in your condenser.