Any setting on the HVAC that includes the defrost symbol will run the compressor to dehumidify the air to help defog the windows - even at 38F.

 

Yes, the clutch is on the front. When it is disingaged the pulley just free wheels as the belt spins it.
When it is energized you should hear it click it is engaged.

You could have some loose wiring/plug. I think if you are low on Freon it will give you the problems you
are experiencing. Iam no AC expert, just things I remember reading.

One of the big guns should come along soon...


Charlie

 

 

 

ok, max ac or normal ac, any setting with the defrost symbol will run the compressor. With an ambient temp of 38f or the heat blend door selected to heat will cause the compressor to cycle on/off quite a bit. The reason for this is in low air flow through the evaporator (blend door on heat position) and/or the low ambient temperature causes low Freon pressures tripping the clutch cycling switch, thus the on/off compressor action. The only thing that does not seem normal is you are getting cold vent temps with the blend door selector set to hot. You should be getting hot air even with the a/c compressor cycling on/off a bit. Check you blend door cable or motor depending on how your year truck is set up.

 

My '88 IDI van also cycles the AC when it's on anything but NORMAL VENT. So if I put it on defrost and heat, the dumb air conditioner turns on. Talk about a waste of MPG and energy, especially in cold climates. If I were the OP, I would install a shut-off switch in the cab on the pigtail to the compressor for the winter. In September, I'd open the switch, then in April, I'd flip it back on.