AC refrigerant temperature switch

[Dragoon GST]

Okay I did some searches but only seemed to find stuff on coolant temperature switches. My AC doesn't work. The fans cut on but it just blows outside air. I recently took it in for a charge to see if that would fix it but it didn't, and after about 3 hours my mechanic said he thought he found it. He says he thought that the refrigerant temperature switch was bad and needed to be replaced.

The part and the labor added up to $400 so I wanted to check here before actually doing this. Does this seem correct? Is there even a part like that, or is that the coolant temperature switch and would that cause the AC to not work? Basically it looks like a power issue to me as the passenger radiator fan clicks and clicks trying to come on but never does. Any AC pros out there?

 

[alex1090]

Whats the original problem you brought it to the shop for?. Does the compressor come on? Does it blow cold at all. Was he tring to fix a leak??

 

[1stGenTSi]

First there is no "AC Temp switch" there are low and high side pressure switches which will turn the compressor off if pressures are too low or too high. Now I'm not sure about 2g dsm's but typically cars with an automatic a/c system will have an AC Temp Sensor which uses a temperature probe on the a/c evaporator. This is used by automatic ac systems to determine when and how often to engage the ac compressor. So if your mechanic believes that the temp sensor is bad which is causing the compressor to turn off or not come on at all then $400 is probably a reasonable price to evacuate the system, remove the evaporator core, replace the sensor and recharge the system. Although if the 2g indeed does have a temp sensor on the evaporator, I don't see this part going bad. The best thing to do is verify that your a/c is properly charged and that the compressor engages at all. First connect a set of a/c gauges, then to check for a proper charge you will need to start the car, turn the a/c on full blast, and manually engage the a/c compressor buy putting power directly to the wire going to the coil behind the compressor clutch, or by removing the a/c relay and apply power to the terminal there. Now with the compressor running you will need to check the pressures on the gauges. The pressures should be about 30-50 on the low side and say 150-300 on the high side. The needles on the gauges ought to be parallel to each other, both at an angle like this "\" about 45 degrees from straight up. Anyways, if the pressures are ok then feel the vent, it should be blowing cold air. If pressures are good and air is cold but the a/c compressor won't come on without applying power then you've either got a bad a/c button, relay, pressure switch, or a short in a wire between one of these. An easy thing to do is unplug the pressure switches (located on the metal a/c lines) and put jumper wires between the two terminals on the connectors. This will tell the ecu that the pressures are good and It's safe to operate the compressor. If the compressor comes on when you do this then your low side pressure is too low, high side is too high, or one of the pressure switches is bad. Anyways, there are too many possible causes to list them all but if the mechanic is replacing a "pressure switch" for $400 then that is a total ripoff. Get some more detailed info from the mechanic. Ask if the system is full of refrigerant, and if the compressor comes on and turns back off right away or if it comes on at all. Take it to another garage for a second opinion, many will offer a "free a/c check."

 

[Dragoon GST]

Whats the original problem you brought it to the shop for?. Does the compressor come on? Does it blow cold at all. Was he tring to fix a leak??

I first brought it in because the AC didn't blow cold. It doesn't blow cold at all. Is there a way to check if the compressor comes on instead of just watching the RPMs drop? No leaks that I know of.

Get some more detailed info from the mechanic. Ask if the system is full of refrigerant, and if the compressor comes on and turns back off right away or if it comes on at all. Take it to another garage for a second opinion, many will offer a "free a/c check."

Yea I am pretty horrible with this stuff so I doubt I will be able to run the tests which you said. I'll try though. I will call the guy back and double check what he was talking about. I wrote down what he said in my cell phone though so I would know exactly what to ask you guys. He said "Your refrigerant temperature switch on your AC compressor is bad and needs to be replaced. The part is special order and costs $180 and it will be about $175 for labor".

So that switch doesn't exist eh?

 

[redyute1]

well first it is called the expansion valve,the problem is by just reading your posts we cannot be 100% sure cause there are so many possibilities,so many tests to run before you sell a customer a $400.00 dollar job only to find out that does not fix the problem,i noticed you are in the mid atlantic area down in va dont know how close that is to me but if you want to make the drive to the shop where i work at i would be happy to check it out for ya and definately save you a bunch of money on that, gimme a pm and we will see whats up

just to clarify the expansion valve works like a temperature sensor or i guess you can call it that, but this guy makes me kinda suspicious cause it is located on the evaporator core and not on the compressor and like i said it seldom goes bad all it does is measure the temperature of the evaporator core in order to cycle the compressor efficiently

 

[Dragoon GST]

Yea he definitely said it was on the compressor. In fact I told him about dsmtuners.com and he said to try to buy a used compressor if I can't find the switch. I'll have to call him tomorrow and confirm all this, he sounds like he doesnt know what hes talking about or I am completely screwing up his story.

 

[Defiant]

There is a switch in the compressor, mounted under the piping plate and inaccessible while on the engine.

However, your problem is more than likely the out-of-production AC controller.

 

[Dragoon GST]

AC controller? Just curious but why do you suspect that over any other part? Also where is this physically located in the car? I'm sure I could find one used here for a pretty good price.

 

[Defiant]

Because I've had two die. It lives in the cabin, behind the glovbox.

Good luck finding one. PM me if you find two.

 

[alex1090]

just to clarify the expansion valve works like a temperature sensor or i guess you can call it that, but this guy makes me kinda suspicious cause it is located on the evaporator core and not on the compressor and like i said it seldom goes bad all it does is measure the temperature of the evaporator core in order to cycle the compressor efficiently[/QUOTE]

Your right and wrong about the operation of a thermal expansion valve. The TXV is a temp controller "restriction". Its job is to reduce high pressure liquid into low pressure liquid. There is a metered orifice at the expansion valves outlet, but there is also a "plunger" that opens and closes to control the amount of refrigerant that goes through the orifice to the evaporator. It indeed does do its job depending on the temp of the refrigerant, but its sole purpose is not to make sure the compressor is working efficiently. Its job is to regulate the flow of refrigerant that enters the evaporator depending on temp.

 

[bastarddsm]

do 1g's suffer froma similar problem?

 

[alex1090]

First things first. To figure out the problem you cant keep guessing and throwing parts at it.
1. Is the system full?
2. Is the system retrofitted to 134a?
3. Do you have power and ground to the compressor?
Number 3 is the first one to check.
Start there and let me know what you find.

Your car is 143a. Didnt see that it was a 96

 

[gbean120]

Sorry to bring this back from the dead, but its summer and my AC does not work. I posted this same problem on a different forum, but I think it was the wrong forum.

My dad is driving my GST around in Palm Springs and the AC is blowing hot air. My mechanic pointed out that the high side was high and he could fix it but could not tell me how much it would cost. I would just need to throw him a blank check. I figured I would probably do a better job so I left and my dad got some gauges and vacuum pump.

I have since pulled a vacuum and charged it back up. But then my low side pressure hit about 75psi, and it was blowing about 70-80deg when the outside air temp was about 95deg. After reviewing the forums I figured I had too much refrigerant, even though I only put in 24 oz. I still have a lot of oil in the system, so I figured that was taking up some room I the lines. I let out a bit of refrigerant and the problem got a bit worse. I let out more and it blows outside air temp (about 100 deg).

My question is, when I charge it to the correct amount, 24oz, what could cause 75psi low side pressure? TXV? A/C controller? Its not the compressor, that cycles on and off.

 

[96eclipzGsT]

Sorry to bring this back from the dead, but its summer and my AC does not work. I posted this same problem on a different forum, but I think it was the wrong forum.

My dad is driving my GST around in Palm Springs and the AC is blowing hot air. My mechanic pointed out that the high side was high and he could fix it but could not tell me how much it would cost. I would just need to throw him a blank check. I figured I would probably do a better job so I left and my dad got some gauges and vacuum pump.

I have since pulled a vacuum and charged it back up. But then my low side pressure hit about 75psi, and it was blowing about 70-80deg when the outside air temp was about 95deg. After reviewing the forums I figured I had too much refrigerant, even though I only put in 24 oz. I still have a lot of oil in the system, so I figured that was taking up some room I the lines. I let out a bit of refrigerant and the problem got a bit worse. I let out more and it blows outside air temp (about 100 deg).

My question is, when I charge it to the correct amount, 24oz, what could cause 75psi low side pressure? TXV? A/C controller? Its not the compressor, that cycles on and off.

A/C work is fairly easy. If the low side is at 75 it is either way overcharged or the compressor is not kicking on. You can look at the front of the a/c compressor and see if it is spinning. The low side should be 45-50psi. You really need a high side gauge too, this way you can tell if there is a blockage or something.(Too much oil will show also) High side should be around 350psi. There should be an a/c sticker under the hood to tell you how much freon the system holds. I think it may only hold around 28 oz, completely empty.

PM me if you need some help. If it is holding freon and compressor kicks on it should be a fairly inexpensive fix.

 

[gbean120]

Thanks for the reply!

What will too much oil show?

 

[96eclipzGsT]

Thanks for the reply!

What will too much oil show?

The pressure on the high side will be a lot higher. Once the pressure gets to high it will kick the compressor off.

 

[gbean120]

That sounds like my problem. How do I drain the oil?

 

[96eclipzGsT]

That sounds like my problem. How do I drain the oil?

I would break the lines off the back of the compressor SLOWLY to drain the system. You can reach them while the compressor is still on the car. Would also replace the dryer if I had the money. (under driver side fender well about 60 bucks) Pull lines off expansion valve which is where the lines run in the firewall next to the evap core. Flush all lines condensor and evap core with some kind of detergent. I have always just used break clean and an air compressor. Break clean evaporates quickly. Replace o-rings on everything I broke loose, put about 4 oz of oil back in the new dryer, put back together, evacuate system if you have a pump, if not just charge back up. My 96 holds 32 oz which is about 2 1/2-3 cans.

Make sure the cans of freon you use don't have any oil in them.
Don't get any detergent in the compressor or expansion valve.

 

[gbean120]

Thanks...thats great info!