: NEED HELP. Air Conditioning

06-13-11, 07:23 PM
okay, so I had my AC switched over from R12, all kinds of new bits in there. The gentlemen at the shop said my Blower Motor Resistor Switch was causing a problem and depending on which way they had it hooked up, I was not getting the blower motor to turn on or not getting the display to the rest of the unit.

To solve this, they rigged a switch (By drilling into one of my interior panels...bastards) to make the blower motor kick on. This switch is set with a relay connecting it to the ignition, so it cannot be left on, yadda, yadda, yadda and controls a GROUND cable, thus allowing the blower motor to be switched on.

Okay, so with this switch, I can manually start the blower motor and cannot do anything else, so I went to the Junkyard for some new Blower Motor Resistor Switches, since they run over $200 new. Grabbed a handful, returned home, hooked them up and still, all three behave the same way. Either these things are ridiculously fragile or something else is up. As is, the AC control panel lights up and changes settings. When I turn it on HI, it makes a faint CLUNK noise, but still the compressor does not kick in NOR does the blower motor. Does anyone else have any idea why the blower motor does not turn on and the compressor does not kick in? I would like to troubleshoot thoroughly before going and buying that stupid switch.

06-14-11, 10:56 AM
sounds like it is an issue with low r134a or they didn't replace all the r12 stuff with 134a compatible stuff

06-14-11, 11:50 PM
Okay, so being new to the world of AC units, precisely what may they have been supposed to change that they did not?

A list of all possible culprits would be appreciated, because the place I went specializes in AC apparently and insisted I needed a new Blower Motor Resistor Switch. I pulled two from the junkyard and with ANY of them, I get the same result. No blower motor, no compressor. This MAY be the problem, but again, since that part is expensive, I want to be certain.

Does anyone know the proper means of testing the compressor and the resistor switch? (I know the blower motor works, because of the switch they installed)

06-17-11, 10:49 AM
Well to get technical you are supposed to change your compressor, hoses, seals/ orings and flush the system since the oil from r-12 reacts with the r-134a to create some gunk stuff that destroys things in your ac. The reason for changing stuff out is that the r-134a molecule is smaller and the seals hoses etc are not made to stop stuff that small. I went through your same situation when converting my blazer to r134a and it never cooled well again and my compressor died not even a year after doing the conversion.

"There are drawbacks to R134a in R12 systems. R134a moves much less heat than R12, which means that your R12 system's effectiveness will be sharply cut. The oil required for 134a reacts poorly with residues that cannot be flushed from a system that has run on R12. This reaction breaks down the oil and frequently destroys the compressor. There are other problems with retrofits. Someone on the Saturn forums I am on did a really good write up on what all you have to do for the ac as he is an ac guy but I can't find it but this one below popped up.

The best method of repairing an R-12 system is still to repair any problems and use R-12 [note: this was written in the late 1990s]. The cost-per-pound savings of the less-expensive R134a are more than eaten up in changeover service work and reversed in failures that are almost guaranteed to happen.

* You might get a mechanic saying that conversion to 134a is just a matter of vacuuming the system and putting in 134a. RUN.
* You might run into someone who wants to replace your R12 with "FR-12" or "Freeze-12" or "Frigc." These three (and several others) are simply 134a with an additive that makes it slightly less violently incompatible with mineral oil. RUN.
* You might also get someone who wants to put OZ-12 or HC-12 into the system. These two are blends of isobutane and isopropane. They work very well in R-12 systems, and have no oil incompatibility problems. BUT, they are flammable. To what degree this concerns you is an individual matter.

It's not as clear-cut as you might think, because all refrigerants are blended with oil in the actual system, and all refrigerants are violently flammable under catastrophic system breach conditions (refrigerant rushes out, creating aerosol mist of oil--BIG flameball whether it's R12, R134a, OZ-12, or whatever). These hydrocarbon blends also are cheap (about $1.25 for enough to charge a few systems), BUT they aren't approved by the regulatory bodies for use in auto A/C systems. "

06-19-11, 08:37 PM
As of now, that should all have been done. I contacted the shop and had them order the part for the massive pricetag. I am dropping it off this Wednesday and if they are correct, a simple swap of the switch should solve everything. If it does NOT, then once they get it all running, I will retry all of the switches that I now have (As the Junkyard had plenty) as I have already tried all of them, but still no go. If hypothetically speaking, that IS the circumstance and one of my switched DOES work, I am not paying for the part. Simple as that.

06-20-11, 01:25 PM
Your invoice will show what all parts they ordered so that will tell you all that you need to know as to what was replaced.