Ac Problems

[tpnotch420]

92 SC400 my blower motor seems to be stuck on low. I have checked both the resistor and the power transistor and both checked out good per my service manual. I ran the Cliamte control diagnostics and came up with pressure switch problem. I'm pretty sure it'slow on freon. So when I try to add freon the gages indicate it's full so I think there is air in the line. From my research I've concluded that I probably need to get a vacuum pump to remove the air before I can refill it but I'm not sure.If there is another less expensive way to fix that I'm all ears as cash is tight right now. On the blower motor speeds I can't seem to find anything else that could be causing the problem. Is it possible that the low freon is causing this not to function as well or do I have a problem with my ECU?

Sorry I forgot tomention that this system has been converted to134a before I got it and the ac worked fine for the last 3 or 4 summers

Any help would be appreciated

[George_Jetson]

Unless you have opened your system, there is a very low probability that there is air in it. When you hooked up the gauge set, what were the high/low sides pressures? Make sure to have the engine running at a fast idle before checking, 1200rpm or so. I would suspect that you have a bad connection, bad switch, or the climate control itself is hosed. With the last possibility, I think that looking at the blower issuse should be put on hold for the moment. Focus on pressure switch issue.

[tpnotch420]

I have not had a chance to get a set of gauges to check yet. I'm still looking for somewhere to pick them up

[George_Jetson]

Harbor Freight sells a cheap set, very marginal quality, but it does work. I always recomend wearing safety glasses when working around compressed gasses. Better safe than sorry.

[jzz30]

is your ac still cold? if its just stuck on low fan speed its the fan speed controller. its a little circuit board that the temperature control knob is on. you have to replace that. the fan speed is controlled by the climate control.