1969 Chevelle Malibu A/C Pump won't stay on!!!

If I jump power from the Battery to the Compressor, it blows nice, cold air. When I remove power from the battery, compressor shuts off (a few months ago pump would stay running after 12v was removed.)

So its acting like a low system charge?

Yes! But I think it is more electrical related. Are the dash switches a common problem. I don't have any power to the pump.

Check from the switch that turns on the pump. If you get no power check that you have power to the switch. Trace it out until you find the problem.

Also if its been converted from the old R12, you may want to verify you have the right high and low pressure switches.

Yes, it was recently converted to r-134a. Pardon my lack of knowledge on this sort of thing, but where/how do I change the pressure switches. Thanks

That was going on the assumption that when someone converted it to R134a, they also replaced the POA valve to a cycling clutch switch. I found this on ebay...poa valve (http://cgi.ebay.com/ebaymotors/66-67-68-69-70-71-72-73-CHEVELLE-A-C-POA-VALVE-KIT_W0QQcmdZViewItemQQcategoryZ33543QQihZ008QQitem Z180230739012QQrdZ1QQsspagenameZWDVW)
You may not have the switch(es) if yours was just recalibrated to use R134a.

You need to know what the problem is to fix it. If its the pressure switch unplug it and put a jumper on it. If the compressor runs it is either low on refrigerant or the wrong switch. If it ran good last summer I would vote for a low charge.

Thanks for all of your great info. Will troubshoot next week. I will post results later.

What did you end up finding on this??

I believe that the r12 was not evacuated properly(when it was converted to 134A). The compressor kicks on 50% of the time and blows cold. The other 50% of the time you have nothing. When you let pressure off of the high pressure side a cream color "pudding" comes out. I would imagine that I will be replacing the entire system at some point. That's my luck!!!

I believe that the r12 was not evacuated properly(when it was converted to 134A). The compressor kicks on 50% of the time and blows cold. The other 50% of the time you have nothing. When you let pressure off of the high pressure side a cream color "pudding" comes out. I would imagine that I will be replacing the entire system at some point. That's my luck!!!

I know they make stuff to actually flush the gunk out of the system. I never had to use it so I don't know how it works.

...AF keeps throwing an error whenever I try to respond to your PM....:screwy:
..I guess I'll try again later...