I have a 94 with a 3vze. The A/C has already been converted to 134a. Vacuumed the system with gauges and input about 24oz of 134a freon. High side went to about 200, low side only to 25. Funny thing is that it cools great going down the highway (41 degrees at vent), but puttering through the woods the vent temperature goes up to 60 degrees. The 41 degree temp while moving tells me the cooling system is working. The evaporator and radiator look okay. Any suggestions as to what is wrong?

 

How's your fan & shroud? If your fan clutch is going, that could be part of it.

Also, there is a cutoff switch under the pax side dash that tells the compressor to switch off below a certain RPM (adjustable) to avoid damage. What's your idle set at?

 

I could be wrong but I think yours has an electric fan on the condenser. Make sure it's coming on and the condenser isn't clogged.

 

Amplifier...there's a knob on it for adjusting cutoff RPM.

 

MIne did the same thing, adjust the RPMs and it now blows cold when idle.

 

Fan and shroud are in good shape. The fan clutch is also good (can't stop it by hand). Idle is about 750rpm, I think.

Is the rpm adjustment knob on the dash or under it?

 

It's up under the dash.

:wabbit2:

 

i run r22 (stuff that goes in freezer trucks ) so cold ice gets on the vents some days little unnecessary but hey if you can get it and you want your truck to pull double duty as a freezer go for it

 

Amplifier is on top of the 'cooling unit' on page 1 here. Just need to pull the glove box to get to it.

Also check the condenser fan if yours has one.

 

Does your idle speed bump up when you turn on the AC?