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Old 04-21-2003, 03:31 AM
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Air conditioning - always high and cold/high hot

1985 (CA) 300TDT wagon. AC was converted to 134. Coldness was just ok. But alway blew high/cold, no matter what temp dial said (MIN or whatever). Changed monovalve element AND checked connection to AUX water pump. Did not check to see if pump turns. Pin connector had been soaked with oil as was pump. cleaned pump, and pins - put back together. Now I get all heat (adjustable with dial) but no cold air. As before when all I had was cold (before monovalve repair) lots of air came out of defrost vents - top of dash. Now with heat - similar air pattern. Can I be certain that AUX pump works? Can crud (oil) on pin connectors cause high amp draw on ACC - frying it? Again with GREAT heat - is pump okay? Was the new heat a combo of monovalve AND cleaning pins? And maybe the ACC is still not okay? Thanks, Steve

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Old 04-21-2003, 07:51 AM
LarryBible
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If you have solid heat, the problem is more likely related to the monovalve than the aux pump. The monovalve failing causes heat all the time, not cold all the time.

Squeeze block the hose leading to the monovalve and see if you again make cold air. If so, pull the top off the monovalve and see if it is flooded. If you don't make cold air with it blocked, check the a/c charge.

Good luck,
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Old 04-21-2003, 10:06 AM
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If you never get air out of the center vents, it's possible the vacuum pod diaphragm has failed. Or you may have other leaks in the ACC vacuum system, as the "default" position is air coming out the defrost vents (cold or hot).

If you can turn the heat off, your monovalve is probably OK. I'd suspect your pushbutton unit, as after 15+ years the 123 p/b units are failing more & more often - they get cranky at first, then get worse. The "aux" pump does NOTHING except keep hot coolant pushed through the heater core at idle - so forget looking at that unless you're complaining about lack of heat at long stop lights.

Is the A/C compressor turning on? If so, you probably have *some* charge in there. Wouldn't hurt to buy the R-134a recharge kit that includes a gauge, and pop that on the low side hose - the reading will tell you if your system is charged or not.


Good luck,
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Old 04-22-2003, 01:13 AM
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You think the (new) monovalve insert is defective? I changed that on Saturday prior to the "No Heat" situation. Now it seems that I can get (very) hot air all the time (no matter what the temp dial says), and I get cool air only if I'm lucky. Question - will hot air "take over" if ac (charge) is low and compressor is not running? I have not checked this yet. Thanks again. I did say "cool" air.

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