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Problem with a custom setup not cooling well

fast400 on Sun May 22, 2011 4:37 PM User is offline

Year: 1969
Make: Pontiac
Model: Firebird
Engine Size: 326`
Refrigerant Type: r134a
Ambient Temp: 75
Pressure Low: 20
Pressure High: 160

I have a 69 Firebird with a LS engine. I've decided to keep the original A/C setup and use it with my swap. I'm using a Sanden 508 compressor, universal condensor, factory evaporator, and a "old air" POA valve retrofit with a low pressure switch incorporated. Everything else is factory except for the custom made hoses.
Considering that everything was new, I vacuumed the system for about an hour, then started filling with r134a. When I filled it the outside temp were 60's. The pressure readings were about 15psi L and 150psi H.
Today I finished wiring the compressor through the low pressure switch, and I'm noticing two things. 1. The compressor cycles on for maybe 5sec then off for 15sec then back on for maybe 20-30sec basically cycling alot (temps in the 70's today). 2. I noticed I'm not cooling much at all...very minimally noticeable. I bridged the low pressure switch to keep the compressor running a little longer, but still little cooling. 3. The high side pressure creeped up to 250psi while I had the switch bridged, but then slowly dropped back down to 160psi on it's own.
I am not an expert at A/C systems at please help!
Here's the car:
Toward's the middle you can get a quick glimpse of the A/C setup.

Stay Cool...

Dougflas on Sun May 22, 2011 11:43 PM User is offline

That AC system isn't large enough to cool the neighborhood. After you install doors and glass, have higher ambient temp, retest. I would think your short on charge right now. The present conditions are not good to evaluate this syem. Is your POA device an eliminator?

fast400 on Mon May 23, 2011 8:59 AM User is offline

The video is is in...LOL!
Guess I'll have to post a new one

Stay Cool...

bohica2xo on Mon May 23, 2011 2:52 PM User is offline

You would appear to be somewhat undercharged.

If the cycling & pressures were at idle, you need to re-test with an engine speed of 1800 rpm or greater.

If it cycles, jumper the low pressure switch - but just long enough to get a steady low side reading! Record the Low & High side pressures, ambient temp & post them.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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