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A bit confusing Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 2 Sep 2005 09:54:55
In Reply to: A/C Problem-Compressor won't engage after repair, Jay, Fri, 2 Sep 2005 09:08:13 Members do not see ads below this line. - Help Keep This Site Online - Signup |
OK, I assume that you have the Manual climate control - knobs, a button for A/C, that sort of thing.
The AC clutch is controlled by a relay. That relay only turns on when the fan switch is on (settings 1-4). Some explaination - the blower fan speed is set by resistors on that fan switch - at 1, all the resistors are in series with the fan motor, and it turns slowly; as you go to 3, more resistors are switched out. At 4, no resistors are in the circuit - the fan gets battery voltage.
The relay knows this, because it is connected to the "1" setting on the switch. It gets 12 volts when set to 1. At settings 2 and 3, the relay still 'sees' the voltage through the resistors. At '4', the relay sees the voltage through the resistors and a thermal fuse on the resistors.
From your first description, I think the blower motor was just fine. The problem was the thermal fuse on the resistor pack had blown. The fan isn't connected to the resistors in positions 1-3. At position 4, the switch connects power directly to the fan and it runs; but the AC relay can't see the voltage, because the thermal fuse is dead.
Given that the blower motor was just fine and the resistor pack thermal fuse was dead, exactly what repair was done? If the resistor pack was replaced, all should work fine. If the blower motor was replaced, it was the wrong repair, because the old motor was just fine.
My question - does the fan speed switch control the fan speed? Can you make it go slow at 1 and fast at 4? If so, then the resistor pack is in there. As to why the AC system isn't working, it all depends. If the mechanic replaced the blower motor, the AC condensor must be moved. It is possible that the mechanic may have disturbed the anti-freeze-up switch, or worse, caused a leak in the system. If the freon pressure is low, the AC system won't engage. The only other thing I can think of is the mechanic did some re-wiring of the system - unlikely, but all I can come up with.
I would go to the mechanic and ask EXACTLY what he/she/it did. What did they replace? What troubleshooting did they do? I think all that needed replacement was the fan resistor module (about $75 for the part, and all of 10 minutes of work).
posted by 192.249....
, Fri, 2 Sep 2005 09:54:55 <-- Viewing This Message, Fri, 2 Sep 2005 14:34:42
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