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Old 09-12-2011, 06:44 AM
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AC runs cold; then drops off...

I have a generation 1 vintage air system in the street rod I purchased a few months ago. I went on a long drive yesterday and it was warm enough out to turn the AC on. At first the air was nice and cool when it started up but after about 20 minutes it dropped off a lot to where it was barely cool at all.
Is it possible that the freon needs a re-charge or is there some other problem with it?
If it needs a recharge how do I get that done seeing as it has the older now not legal refrigerant in it?
Any help is appreciated.

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Old 09-12-2011, 01:36 PM
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Quote:
Originally Posted by maddog48merc
I have a generation 1 vintage air system in the street rod I purchased a few months ago. I went on a long drive yesterday and it was warm enough out to turn the AC on. At first the air was nice and cool when it started up but after about 20 minutes it dropped off a lot to where it was barely cool at all.
Is it possible that the freon needs a re-charge or is there some other problem with it?
If it needs a recharge how do I get that done seeing as it has the older now not legal refrigerant in it?
Any help is appreciated.
You need to find someone with gauges to know for sure. Lack of air flow across the condenser will cause it to gradually heat up and effect efficiency.
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Old 09-12-2011, 02:20 PM
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Might be able to retrofit it to r-134.
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Old 09-12-2011, 05:06 PM
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Seems to me it could be a problem with the hot water valve passing water through the heater core.
I would check there first.
After a few minutes the engine warms up and then heats the air conditioned air, cancelling it out.
If the system has a temp blend door , check to see if it is closing off the heat side while allowing the AC side to function.
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Old 09-12-2011, 05:57 PM
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WOW thanks for the quick replies.

T-bucket23
The condenser is located in front of the radiator so I'm pretty sure it is getting a good supply of air; there is also a fan on the engine to help with flow; and an electric fan in front of the radiator also that I turn on when I turn on the AC.

latech
The system doesn't have a blend on it; there is a vacuum line that opens a valve for the hot water when I want heat for the unit.
This is a very simple AC set up; it has a 3-speed fan and 3 controls for the AC unit.
EC (for economy using just the air in the car)
AC (for the air conditioning); and
HE (for heat when I want to warm things up).

Keep the ideas coming though guys.
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Old 09-12-2011, 06:07 PM
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lack of a blend door would mean that if the hot water valve failed and allowed hot water to pass to the heater core when not wanted, could cause exactly the trouble youre having.Just a thought.
The system could be plugging up as its running also, and as T bucket said , you would need gauges to diagnose that.
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Old 09-12-2011, 08:25 PM
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Maybe icing up?? Does that system use a suction throttling valve?
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Old 09-13-2011, 11:11 AM
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i found vintage air tech support to be one of the best.
give them a call
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