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AC Low Pressure Switch keeps failing

 
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Old 06 Jul 2018, 11:33 am
falconut's Avatar
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Default AC Low Pressure Switch keeps failing

Maybe somebody here can give me some areas to look into. My son now drives my 2007 base PT, but only really uses it as a back and forth vehicle, so not a lot of mileage. A couple weeks ago the AC just stopped. The compressor wasn't turning on. I replaced the low pressure switch and it started working again, I also checked the charge and it was around 40psi, so in the range.

About a week later he drive the car (1st time since replacing switch) and drove about 30 miles & it worked fine. On the way home it stopped almost immediately. I exchanged the switch for a new one and it worked fine again.

A couple days later he drove it again and this time it stopped almost immediately after turning it on. Any ideas as to what could be casing the switch to fail? I doubt I got 2 defective switches. Any help would be appreciated.
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Old 12 Jul 2018, 11:14 am
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Default Re: AC Low Pressure Switch keeps failing

I'm guessing this isn't a common occurrence.
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Old 24 Jul 2018, 11:17 am
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Default Re: AC Low Pressure Switch keeps failing

Sometimes it's the plug and not the device that needs fixing. Try disconnecting the plug, spraying a little contact cleaner into it and plugging it back in. If it start working again, maybe you could inspect the plug contacts to make sure they're clean and that the plug contacts are not bent out of shape.

My younger son's newly purchased 07 Camry A/C stopped working while in Kansas. At first he said the A/C was dead but with some probing, I got him to narrow it down to the blower not working. I read up that the blower connector can get flaky so I told him to give a medium whack to the panel below the glove compartment but only once. It's been working all summer which is good because the midwest has had record heat this year. Had I been out there I would have disconnected the plug, cleaned the contacts and see if they needed to be rebent to make better contact.

There are numerous camshaft position sensor problems that come up and sometimes just unplugging and reinserting the sensor plug fixes it.

Good luck
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Old 24 Jul 2018, 11:19 pm
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Default Re: AC Low Pressure Switch keeps failing

Un plug the plug for the switch and jump the wires in the plug. Turn start the car and turn on the air. The commpressor should be running. If it is then put a meter on the switch and see if it is shorted or open.

If it is open then the switch is bad but I don't know how you could get so many bad switches.

If the switch is shorted while the air is on. I would leave the jumper in place for a bit. If you still have issues then as the previous post suggest, try cleaning the plug.

And make sure the switch is all the way tightened down. Don't reef on it. It is plastic. If it is not all the way tightened it won't work. The switch depresses a valve as it tightens down.

Last edited by 1911ly; 24 Jul 2018 at 11:23 pm.
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Old 27 Jul 2018, 07:41 pm
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Default Re: AC Low Pressure Switch keeps failing

I tried to jump the connector using a paper clip, but it never worked. This was before i swapped the switches.

Here's the crazy part, my son was driving on monday & had it on for defroster blowing warm, then it just started working & blew cold for like 10 minutes, then stopped. Next time he drove it was Wednesday & he said it worked the whole time. He drives are aboutv40 minutes.

This car has had some weird grounding issues over the past couple of years where I've had to add new ground wires to some the issues. I'm starting to think this is the problem.
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Old 30 Jul 2018, 07:30 am
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Default Intermittent a/c operation

First of all, be sure your radiator fan turns on at high speed when the A/C button is pressed and the A/C light turns on. Have someone listen for the A/C clutch to clank when the button is pressed. Chances are the clutch and compressor is working because you get cool air some of the time. Did you ever try to add refrigerant to the system? If yes, it may be overfilled.

You should do a pressure check on the system to make sure you have the proper amount of R134a in the system. You want enough but not too much. You could get a dual A/C pressure gauge, one that measures the high side and the low side, as a loaner from some auto parts stores or about $50-$80 if you want to own one.



Your A/C compressor will stop working when the refrigerant pressure is either too high or too low. Make sure you check the readings both at rest and with the engine running and the A/C working. It's best to do this in the morning when it's cool rather than in 100 degree heat.
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Old 31 Jul 2018, 10:01 pm
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Default Re: AC Low Pressure Switch keeps failing

I had the radiator fan a while back & when it was bad the air blew hot at idol then cold when moving. This isn't doing this, this time, plus when I was initially checking it, the compressor never turned on. As soon as I installed the new switch, it clicked on.

I had a recharge kit with the gauge & once it started running, it was at 40 psi. Which was close to the pressure it was supposed to be according to the temp that day. It has me baffled, but we'll see how it does the next day it's used.
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Old 04 Aug 2018, 02:19 pm
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Default Re: AC Low Pressure Switch keeps failing

Have you changed the receiver/drier in the cars lifetime...?

Has the system ever been opened, or had a leak...?

As a rule of thumb, you're gambling your compressor if you don't replace the R/D when the system has been "open" for anything more than a few minutes.
R/D = cheap -v- compressor = arm and a leg, and then there's fitting it...

If the system has been opened, and the R/D is the original, you should think about changing it for a new one. You've definitely got something up in that corner, and it could be the R/D has had it's day.

For instance... It might have burst internally and it's desiccant / crap in the Schrader valve that's under the LPS that's causing your problem...

It might just be blocked solid, and freezing / thawing / freezing... giving you blow hot/blow cold
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Old 11 Aug 2018, 09:12 pm
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Default Re: AC Low Pressure Switch keeps failing

The only thing that was replaced was a hose that the dealer broke doing the timing belt. Systems always been solid, no leaks. My son said it wasn't working again last week. The electrical system on this thing has caused me some headaches over the last few years. I'm guessing this is just another one of those times.
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Old 17 Aug 2018, 06:53 am
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Default Re: Intermittent a/c operation

Quote:
Originally Posted by rsrocket1 View Post
First of all, be sure your radiator fan turns on at high speed when the A/C button is pressed and the A/C light turns on. Have someone listen for the A/C clutch to clank when the button is pressed. Chances are the clutch and compressor is working because you get cool air some of the time. Did you ever try to add refrigerant to the system? If yes, it may be overfilled.
OK, so I looked at this yesterday. I started the car up and let it idle for about 5 minutes to warm up. I turned the AC on and it doesn't sound like the hi speed fan ever kicked on. Clicked the AC button on & off several times, along with moved the temperature up & down to be sure, but never heard the hi speed kick on. Neither did the compressor, so neither the hi speed fan nor the compressor turned on.

Question: Doesn't the compressor still turn on, even when the hi speed fan is bad? The car has been driven in 95+ temps and no overheating issues, but no AC when idle or moving at 70mph+. Just looking for clarification.
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