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High pressure problem- erratic fan cycling= related? pls help

TUSKMAN79 on Mon August 31, 2009 9:40 PM User is offline

Year: 1994
Engine Size: 3.8
Refrigerant Type: R134A
Ambient Temp: 70
Pressure Low: 55
Pressure High: 300
Country of Origin: United States

My a/c system ('94 T&C 3.8Liter) had a leaking seal on the rear a/c floor block which I repalced, I evacuated and recahrged, and leak tested the system. I have a dual gauge manfiold and am showing high pressure readings on the high and low sides. low runs 50-55 psi, high 250-300 psi. I only got 3 cans in (35-39 oz) which is less than a full charge (52 oz) before stopping because of high pressures. it is not blowing cold yet. I think the problem may be with the electric condenser fan. It kicks on in a regular pattern (maybe every 20-30 secs) then kicks off within 3-5 secs. it never stays on longer than that. when it does kick on the pressure on both sides starts to drop immediately, but then the fan kicks right off and the pressures rise again. Also the A/C compressor runs continously (once an adequate refrigerant charge is put in) if the A.c is turned on, which I'm not sure is correct. With the A/C switched OFF, the fan turns on for much longer periods as it normally would. No overheating problems. Is my high a/c pressure caused by the fan not functioning properly and thus the refigerant not cooling in the condenser (I was doing this in park so no air moving), or could there be an additional problem? Why does the fan behave erratically with the A/C on but work normal with it off? There must be a sensor or switch to tell it when to come on that is confused?
any help would be welcome. My low pressure compressor cutout swtich is working as the compressor does not kick on if the system low. thanks!

Chick on Mon August 31, 2009 9:59 PM User is offlineView users profile

It is dropping out when the high side pressure falls, try to get the full charge in and watch if the pressure drops when the fan is running..I think you are just undercharged, thats why it's dropping the pressure so fast... let us know how it works with the full charge in it, unless the high side doesn't drop when the fan come on....

Email: Chick


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