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Re: AC low pressure switch leaking
Sounds about right. The switch itself is relatively cheap -$20-40, what you are paying for is the special handling that is required to remove R12, the labor to remove the switch, vacuuming and refilling the system.
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if you did the recharge then check the gas pressures as there are two main switches that control the ac operation
one is a high pressure switch which stops operation if there is excessive gas or a blockage and the other is a low pressure switch which stops operation if the gas has leaked out
did you have the ac system checked for leaks before gassing it or replacing the ac compressor
lastly some systems have a relay that controls the ac and that can fail
Your system is most likely an R12 system and R12 is very expensive even if you are lucky enough to find it. Most older vehicles are being converted to 134A which you can buy just about any auto parts store, heck they even sell it at Dollar General. It was really cheap at first while there were still a lot of R12 units still on the road but the price has gone up since the R12 has been phased out. This presents a quandary as I don't know if you are just topping off your system or you have had to replace something. AC work should only be done by certified technicians. That said Auto parts stores have the simple can with a gauge for topping off a unit but if more work needs to be done then you have to have gauges, replace the dryer, valve, etc. also if the system has been opened to air. If you overcharge a system you will have too high a head pressure and destroy the compressor too low and it won't cool or the pressure switch will shut the clutch off or it will constantly cycle. There are Federal laws governing AC work plus it could be dangerous of course I would bet there are a ton of you tube videos.
You are bypassing the safety mechanism built in to prevent compressor damage. You either have one of two conditions, You truly have a low pressure condition(menaing you need an evac and recharge(fill the system with r134a gas) or a bad pressure switch. The switches are inexpensive replacing it will cost less than the charge to diagnose it, as such i would have it evacuated change the switch then have it recharged and a UV die added in so any other potential leaks can be found
Must be Air-Condition System Lines/ Hoses leaking R12 Freon (gas). MAYBE THE PULLY HUB BEARINGS FAILED OR DUE TO VERY LOW R12 FREON (GAS ) will not work. Because there is a switch in the receiver/dryer prevent AC from working when low R12 Freon present, to protect the system & compressor damages. You must fix the leaks, before recharging it. They must **** the old (residue) gases from the system & lines / hoses...... & stay in the vacuum pump 30 minutes to proof no more leaks. Recharge some oil for the old type R12 Freon gas. Before recharge it to 62-67 psi R12 Freon See the web site like www.youtube.com/video site to see How they service & repair air-condition system? Put the question to their search window. This is the question u should. How they service & repair air-condition system? Regards; MAR
whenever the ac system has been opened it should be hooked up to a vacuum pump designed to evacuate the ac system of any foreign debris and oil etc and after should be able to hold a vacuum to show that there are in fact no leaks then if all is ok at this point you can then charge your ac with the proper freon specified for you car when the pressure reaches satisfactory level the ac compressor will then cycle on you should not bypass the low pressure switch
You should have R12 freon in a 1990 but you can put R134 freon into that system the only problem your going to have is the adapter for R12 is different from R134 after you get the adapter you need to put the freon in the low pressure valve not the high pressure, you will know which one because the adapter only fits the low pressure valve which is located on your AC lines under your hood, theres a little cap thats either blue or black you unscrew. You can't buy r12 anymore because its not good for enviorment so buy R134. you can buy at any parts store for like $5 to $10.
Sounds like the A/C system just needs to be recharged. When was the last time you had this done? Just take it in to your mechanic and he can do it for you and if that's not it for some reason, then he will be able to find the problem but most likely you need more freon added.