It's been a while since I've been around, out playing with the toys. I came across a problem with my air conditioning yesterday that I just don't get. My truck, while sitting still at idle, has real nice cold air blowing but when I drive the truck it starts blowing warm air. In my limited experience this is bass-akwards from what I would expect.

I have a '53 with a tuned port 350 and a Vintage Air system with the Vintage Air polished compressor.

Any help would be appreciated...


Mark

 

Does the vintage Air unit use electric or vacuum controls?

 

Electric controls

 

Check your compressor belt tension and the clutch plate tension.
Are you running an electric fan? Is the compressor wired through the fan? I've seen situations where the compressor was wired through the fan, and would only run when the fan was on, as in a modern car. The problem with this is, if the fan is wired through a temperature regulated switch, when the engine reaches the set temp, the fan kicks off, shutting off the compressor.

If that's not it, then put some gauges on it and check for off idle restrictions in the system. A plugged orifice tube, expansion valve or receiver/dryer may be the culprit.

 

Assuming this is a pretty new system, those shouldn't be likely culprits, but they certainly fit the symptoms.

Does the system include a switch to turn off the compressor on low vacuum or WOT? These are sometimes there to kill the compressor when you need max power, but if misadjusted or malfunctioning, could be killing the compressor at moderate loads.

Is this a new condition, or is this your first operation of the system?

 

Is there a fresh air vent that is pulling warm air in mass while moving?

 

Giesterfarher™ Check your compressor belt tension and the clutch plate tension.
Are you running an electric fan? Is the compressor wired through the fan? I've seen situations where the compressor was wired through the fan, and would only run when the fan was on, as in a modern car. The problem with this is, if the fan is wired through a temperature regulated switch, when the engine reaches the set temp, the fan kicks off, shutting off the compressor.

If that's not it, then put some gauges on it and check for off idle restrictions in the system. A plugged orifice tube, expansion valve or receiver/dryer may be the culprit.

Giesterfarher- With the Tuned Port I am running a serpentine belt and the tension appears to be fine. I do have an electric fan hooked up and I am not sure at this point if the compressor is wired through it...I will check. The system itself was brand new from Vintage air.

ALBUQ F-1 Does the system include a switch to turn off the compressor on low vacuum or WOT? These are sometimes there to kill the compressor when you need max power, but if misadjusted or malfunctioning, could be killing the compressor at moderate loads.

Is this a new condition, or is this your first operation of the system?

ALBUQ F-1 - I believe the system would have the WOT valve and not the vacuum. and yes the system was brand new from Vintage Air

 

Vintage Air has a pretty good tech line and seeing as it's thier system I'm sure they would give you the right answers.

 

x2 on calling VA. They will ask you to leave your number and they WILL call you back.

 

Check your heater valve. I read a post years ago where the heater valve was installed backwards, the flow going the wrong direction. With a little rpm, the water pump was able to push the valve open, sending hot water to the heater. Also, make sure the valve is in the correct hose. The pressure side, not the return side.

 

I think Vintage Air says that is one of their most confronted problems. Good of you to remember it.