1989 240sx -

Ok, just had my a/c diagnosed, it was working intermittently and now not at all. The service shop said that the compressor thermo switch was not working correctly and therefore the compressor was not working.

They want just over $300 to change this part and recharge the system which I think is pretty high so....

They showed me the part, it is built into the top of the compressor and has 2 wires coming out. Is this something that I could change myself? Has anyone done this, and if so any details would be appreciated!

TIA

Do they have to remove the freon to replace the switch? How much would they charge just to recharge the freon?

The switch is built into the top of the compressor.

Im pretty sure you can do it. At various auto part stores they sell DIY A/C kit. Im not sure what that comes with but if they sell that then its probably simple enough to do it your self. As for the compressor check your local junk yards for a cheap working unit.

first try recharing the system and see if that helps...

Recharging the system won't help if the compressor won't work because of the bad thermo protection switch... I need to change the switch first the get the system recharged. I just want to know how to take the switch out, and if there's anything that I should be aware of before doing it. Has anyone done this?

The compressor is fine otherwise...

Whoa, hold on here. Do NOT convert your system to R-134a unless you remove all the oil, replace all the seals, replace the drier, and have the system thoroughly flushed first. Otherwise, the system will probably break down within a year because of oil and refrigernat incompatibilities. You cannot buy R-12 at Autozone or Pep Boys.

I looked at the '90 manual for the 240; I will assume the '89 is the same.

"The thermal protection switch, installed in the A/C compressor at evaporator refrigerant line inlet, incorportes a pressure diaphragm switch and temperature sensor. When refrigerant temperature increases, temperature sensitive gas inside temperature sensor expands, causing diaphragm switch to open electrical circuit to A/C compressor."

Before you do anything else, verify the shop's diagnosis. Disconnect the switch harness and use an ohmmeter to measure the resistance of the switch at the connector terminals. If the resistance is really high or open, then the shop was right. If the resistance is really low, near zero, then go to another shop.

Assuming the shop was right: The temp switch cannot be removed without opening up the system. Please do not vent R-12 to the atmosphere. Have the system vacuumed out by a shop, and ask them how much oil they removed. They should be willing to do it for free if you agree to come back later for the recharge. You can then remove the switch on your own and replace it, along with the o-ring seal. Lube the seal with mineral oil (baby oil might work) before installation. Then take the car down and have it recharged and oil added. This will probably cost $100-150, but is still cheaper than doing a "proper" R-134a conversion, and the AC will be colder. Try to do the entire job in as little time as possible. Once you remove the switch, moisture will get in and saturate the drier. Ideally, you would want to replace the drier too (I would). It probably costs around $50 for the part and isn't too hard to install.

A good site on AC info, service and repair:

http://autorepair.about.com/li...a.htm

a little off topic, I went to local parts places to buy a sealer/o-ring conditioner for my r12 system but they only have stuff for r134a...

do they sell them anymore? I don't want to convert to that new one until I have a major problem.

You can buy anything for R-12 systems except for the R-12 itself. O-rings, lubricant, dessicant, hoses, gauges, etc. But because the R-12 hasn't been legal for new cars in 10 years, there is less demand, and stores choose not to stock these items. You can go to a specialty AC or maybe even a welding shop for some of these items. Or your nearest dealership. Also, tool houses sell service items.

thanx, D... i would probably find that out myself but just verifying by someone who's currently in that field.

BTW I had one of those ASE cert for purchasing R12 waay back in may '97 (geez that test was too easy back then)."ASE Refrigerant Recovery & Recycling Program" then uses your SS# & MVAC as your certification #...

Shoulda bought some spare cans back then when I recharged my system in '98

Yeah, it's amazing R-12 was almost as cheap then as R-134a is now. Talk about your appreciating investment. The hard part is figuring out when the prices will stop climbing. Eventually the cost will force more and more people to switch to R-134a, plus older cars get "retired" as time goes on. So I have to assume the price will stop climbing once the demand drops faster than the supply. I don't know if your cert is still good, but the test is still fairly easy if you have any interest.

NAPA sells R-12 if you are licensed. I think certificates last 5 years, not 100% sure though.

$300 isn't bad if they are doing and evac and recharge on a R-12 system. The unit will not be able to evac 100% of your a/c charge plus the amount of oil extracted is always not exact.

The other option for your problem is that the clutch is going bad on the a/c compressor. They like to act as you've described when they go.

I had the system converted to R-134 2 years ago. $300 IS bad to evac and recharge this system and change the Thermo Protection Switch. The shop I went to wanted $71 just for the switch and another $88 to install it and $130 to recharge the system. I found the switch for $27 delivered, this is why I wanted to change it myself... From the replies so far, I guess the system needs to be evacuated first, then the switch needs to be replaced, then the system needs to be recharged. I will see if I can get another shop to install the switch and recharge the system for me. Hopefully for about $150 total!