A/C not working

[sieg01]

I could have swore that I tried out the A/C when I was taking a test drive before I bought my vibe month or two ago and that it worked.... But tried the last week when it got hot out and it doesn't blow cold air.


Here is what I have learned so far:

Replaced the relay with the horn relay. Doesn't appear to be that.

RPMs are increasing when I switch on the A/C when it is idleing. Fan comes on.

I do have a P0128 issue on the car. Engine not coming up to temp in time. I was going to replace the tstat for that.... not sure if they are related to this issue.

I pulled of the 4 pin header on the Pressure Switch. When I short pins 2 and 3 together the fan comes on. When I short 1 and 4 together then it sounds like the compressor is turning on. (using the attached pdf)

Anything else to try? Could it need to be recharged? Would the compressor not come on if the pressure was too low?

[trb]

There is a low pressure switch on AC systems that prevents the compressor from engaging if the refrigerant level is too low. This is so it will keep from damaging the compressor. So it sounds like you have a leak. The seller could have charged it up for the sale, and it may have leaked out by now. Best bet is to have it looked at and the leak fixed, or you can just add some more refrigerant, maybe the kind with the dye for leaks. If you are relatively handy, you can work on it yourself if you rent the equipment from someplace like Autozone.

[silverbullet]

Little thread jack for a question.... If it is low causing the compressor not to come on. How do you fill it? Dont you need to run the air and it pulls in the refregirant. x

[trb]

Little thread jack for a question.... If it is low causing the compressor not to come on. How do you fill it? Dont you need to run the air and it pulls in the refregirant. x

If it is so low that it will not cycle the compressor on, you need to jumper the low pressure switch like how it says in the instructions sieg01 posted. That forces the compressor to run and create a vacuum to pull the additional refrigerant into the system.

[sieg01]

I was going to bring it in to have it looked at, but I looked at it a little more first.

How can you tell if the compressor clutch is engaging? I hear the RPMs rev up when I touch the pin 1 and 4 together. But one of my co-workers looked at it and he questioned... should the endcap (?) of the compressor be turning when the compressor clutch engages (when I short the pins). I noticed that it doesn't seem to be moving ever. If that is the compressor clutch that isn't working? What is making the engine rev a little higher?

[trb]

I was going to bring it in to have it looked at, but I looked at it a little more first.

How can you tell if the compressor clutch is engaging? I hear the RPMs rev up when I touch the pin 1 and 4 together. But one of my co-workers looked at it and he questioned... should the endcap (?) of the compressor be turning when the compressor clutch engages (when I short the pins). I noticed that it doesn't seem to be moving ever. If that is the compressor clutch that isn't working? What is making the engine rev a little higher?

The end of the pulley should be turning when the A/C clutch is engaged. The end is directly connected to the internals of the compressor. The belt just freewheels on the pulley until the clutch engages and "locks" the belt part of the pulley to the end part of the pulley. My guess is the increased RPMs are just a result of you bypassing the switch. I know the radiator cooling fan usually comes on when you bypass it also.

If you can reach the end of the pulley with the motor off, try to turn it by hand. If it turns pretty easily, at least the compressor is not locked up and maybe just the A/C clutch failed. If it is really hard to turn or won't turn at all, then the compressor locking up could have burned out the A/C clutch too. Can you check to see if you are getting 12V at the compressor A/C clutch when the A/C is on and the pressure switch is bypassed?

[sieg01]

Well I finally got around to working on it again.

I tried to move the clutch and I can't get it to move at all. Should it be able to move with the belt on?

I am getting 12V at the compressor when it is bypassed.

So that probably means I need a new compressor?

[bluneon]

sounds like it. they're around 200 bucks just for a re-manufactured unit.

[sieg01]

Well I'm going to buy the stuff to do it myself. Already have a vac pump. I'll get the guage set as well. Looks like there are some fairly cheap remanufatured ones on ebay for $130 (http://www.ebay.com/itm/Premium-A-C-Com ... 432wt_1164" onclick="window.open(this.href);return false;) Will that work OK?

Or else there are some cheaper used ones, but something tells me to stay away from the used.

I'm going to replace the belt as well at the time (looks like it has a few nicks in it). Think I should change out the expansion valve as well?

I think I'm going to replace the tstat on the coolant at the same time (been getting a CEL for that) and flush it out. Anything else I should do when I'm in there??

[trb]

Well I finally got around to working on it again.

I tried to move the clutch and I can't get it to move at all. Should it be able to move with the belt on?

I am getting 12V at the compressor when it is bypassed.

So that probably means I need a new compressor?

The end of the pulley should be able to turn with the belt on and the car off, if the compressor is OK. Only the ribbed part of the pulley is held in place by a stationary belt. So if you can't move the end, then the compressor is most likely locked up. I would remove the belt and make sure the compressor will not move at all.

The only caution is that there could be some debris in the lines if the compressor is damaged. Then you might want to flush the lines to make sure there are no metal particles in them that would damage the new compressor or clog the lines.

Good luck!

[sieg01]

Well I got everything done. Flushed the coolant, new thermostat. Replaced Compressor and flushed the lines, then vac it out and added r134a. When I added it I had to jumper the Low pressure switch pin to get the compressor to turn so I could add it. I was getting a low side pressure of 35psi and high side of 225 (a/c on high cold, recirc on), also I get cold air.

When I replaced the pressure switch plug back, the clutch won't engage and no cold air. It seems like I have enough pressure to avoid tripping the low pressure switch... Is there something else I could get wrong?

I also tried swapping the relay with the horn and they both work.

[sieg01]

Also I'm not getting the engine idle rpm increase when I hit the A/C button like I was before. Could my engine be too hot (maybe an air bubble in the line from the flush)?

[trb]

The pressure switch could be bad. I had one fail on my Mustang. No idea on the coolant flush air bubble since I haven't touched that part yet.

[silverbullet]

i might just have to bring this in to the shop but are there any suggestions if jumping the low pressure switch wont get the clutch to engage? the clutch is not seized and the compressor is only just over a year old. i had the freon filled and it worked for two weeks and now the compressor wont come on just like before when it was low. so i assume i must have a small leak, i was just hoping to fill it myself to get by for another couple weeks until i can have the shop look at it again. also is there a good way to check for leaks without buying any special tools? thanks

[trb]

i might just have to bring this in to the shop but are there any suggestions if jumping the low pressure switch wont get the clutch to engage? the clutch is not seized and the compressor is only just over a year old. i had the freon filled and it worked for two weeks and now the compressor wont come on just like before when it was low. so i assume i must have a small leak, i was just hoping to fill it myself to get by for another couple weeks until i can have the shop look at it again. also is there a good way to check for leaks without buying any special tools? thanks

You can add some dye to the system, and then it would show you where it is leaking. Probably an "O" ring that has dried up and letting it leak past it.

But if jumping the pressure switch will not engage the compressor, then there is likely a power issue to the AC clutch. Either a relay or fuse or something. If you have a multimeter, you can check on the pressure switch to see if you are getting 12v when the ac is on.

[sieg01]

Well a little more debugging.

Using that onvien40.pdf I posted before. I hooked a multimeter to the male pins 1 and 4. I jumpered the female side of pins 1 and 4. I read no continuity until I get the high side to 225lbs of pressure (low side is about 40-45). When I disconnect the jumpered wires. I get continuity until about 175lbs (low side is about 70 lbs at that point).

I'm wondering if I put too much oil in the system and it is messing with the pressure measurement?

[sieg01]

Thinking I'm going to order a new low pressure switch. Does anyone know if I have to vac down the system to replace that? Or is there a valve on it? Looks like amazon has a fairly cheap one for $70.

Also when I replaced my compressor, I didn't replace the receiver/drier, I saw people recommended that. Should I do that now?

[djkeev]

Thinking I'm going to order a new low pressure switch. Does anyone know if I have to vac down the system to replace that? Or is there a valve on it? Looks like amazon has a fairly cheap one for $70.

Also when I replaced my compressor, I didn't replace the receiver/drier, I saw people recommended that. Should I do that now?

Yes, you'll need to bleed off the system.

if the compressor went bad a new reciever dryer is highly recommended.

dave

[sieg01]

Replaced the low pressure switch and the drier. When I vacuummed it down I noticed it was leaking somewhere a bit. Took off the drier and checked all the orings and made sure they had oil. Added a bit of freon to it and leaked out. Added a bit more (it seemed to hold the pressure) and left it over night.

This morning, there was a puddle on the driveway of oil. The compressor appears to be leaking around the housing. Adding any freon is instantly leaking out. Did my compressor just die again???? It was holding pressure just find before I changed out the drier and low pressure switch. Would something I did cause the compressor to leak?

crap.