AC problems

[Greg00gts]

Hi,
Anyone have some A/C knowledge. My A/C just stopped working on 07 m35, here is what I know so far.
Heater works great
A/C compressor clutch is not spinning but I am able to move it by hand.
The low pressure side is high (90psi) and the high pressure side is low (90psi)
Does any one know what electric stuff I can check or what may be the problem. Thx

[EdBwoy]

Greg, one thing I would do is to put 12 volts to the clutch to see if it engages. Here's a thread of someone with a similar situation:
cant-get-my-a-c-to-work-help-t616494.html

And if you find yourself needing to do more extensive repairs, steve_c & Sstupid are very knowledgeable and experienced with automotive HVAC.
replacing-ac-compressor-on-2007-m45-t616954.html

[Gene Ln]

A couple of things to remember their is a low pressure switch, and an over pressure switch that kicks off the compressor if your too low or too high. if you have 90psi across both sides of the compressor you may have a problem as the low side is only supposed to run about 45 psi.

But in your case I think your just too low of freon causing the low pressure switch to kick off the compressor. you may have a leak, you could diy with a single can of freon from a parts store (one with a built in quick connect to the a/c system) and see if it will put enough in to make it work. Turn your a/c to max and then connect the freon can.

[Greg00gts]

I took the car in to pep boys for a second opinion. They said the Freon levels are good, all fuses and relays and that the compressor clutch does not engage. That is all the free inspection entailed and they wanted money to do some electrical testing which I denied.

I want to check the compressor clutch my self by checking for the 12volt signal and then see if I can apply the 12v signal directly to the compress.
My question is why does our clutch compressor has two plugs. All the videos online that I’ve seen only have one plug.
Thanks

[Six_Legs]

Your symptoms sound just like mine did back in March. I had to replace the compressor and its not cheap! Luckily I had a month left on my extended warranty and it was covered. I also got a new steering rack out of it. Total amount of warranty work was $4500 with the a/c portion being more than the steering rack.

[Sstupid]

I took the car in to pep boys for a second opinion. They said the Freon levels are good, all fuses and relays and that the compressor clutch does not engage. That is all the free inspection entailed and they wanted money to do some electrical testing which I denied.

I want to check the compressor clutch my self by checking for the 12volt signal and then see if I can apply the 12v signal directly to the compress.
My question is why does our clutch compressor has two plugs. All the videos online that I’ve seen only have one plug.
Thanks

Ed is correct. The first thing you need to do is check that your electromagnetic coil for your compressor clutch is receiving 12 volts when the A/C is turned on. I won't lie and tell you it is easy to get to that wire, because it's not. I think the easiest way is to pull the driver's side wheel and fender liners and gain access that way.

It does sound like your freon pressures are good. Since your clutch is not coming on, you are measuring static pressures on both the low and high sides. With a static check, they are supposed to be the same or within a few pounds of each other, which yours are, and the low-side static pressure is supposed to be between 80-90 psi depending on how cold your engine is, so it sounds like you're good on freon. If there was a delta between the two pressures, statically, it would mean you have a leak somewhere.

Once you figure out if you have 12V at the electromagnetic coil, let us know, and we can continue from there. If you have 12V and your clutch still isn't engaging, then you need to replace the coil. I have written a how-to on that and it's in the FAQ section. It's not the easiest thing in the world to do, but it was pretty cheap compared to replacing the compressor, which I just did a couple of months ago. The coil replacement was about $180, with cost of some tools. The compressor/drier/evaporator replacement cost me around $800, and I had all the tools like the vac pump, gauge set, etc.

There are two plugs on the compressor because one is for the clutch coil and the other is for some kind of pressure sensor in the compressor.

[Sstupid]

Here is a link that will show some pics of the wire you need to check for the coil.

replacing-ac-compressor-on-2007-m45-t616954.html

[Greg00gts]

So here’s where I’m at
I check for the 12v signal (the connector was a pain so I gave up then the next day tried again and had it off in 5sec) checked good!
I would have liked to apply 12v directly to the compressor or even just ohm through the compressor but the connector is in such a bad spot it is almost impossible.
I ordered a kit off amazon about $250 dollar for compressor, dryer, expansion, o rings, and oil. I will be replacing everything this week or so. I’ll post the results.

[Sstupid]

Yeah, your electromagnetic coil went out.

You most likely got the buyautoparts kit, which is what I went with. The dryer is a little bit of a pain to get to. You essentially have to almost remove the radiator to get to it. If you have any questions, let me know. I just got done doing this exact job. You can rent the vac pump at Autozone and it sounds like you already have a gauge set, so you're set to go. Remember, pour out and measure the PAG 46 that comes out of the compressor and dryer and only add back that amount in the system. The compressor they sent you likely came with 4oz of PAG already in it. You'll need to complelely drain that and add back only what you need. Also, don't do like I did and accidentally buy freon that already has PAG oil in it. Make sure you're putting in only pure R134.

You could technically remove just the clutch from the new compressor and put that on the old compressor and probably be fine, but it sounds like you're geared up for the complete install and I certainly won't argue with doing it right.

[Greg00gts]

Thanks you for support. I got a couple of questions rafter reading your comments. Btw m35 07 and yes buyautopartskit.

I will be starting with the “expansion devise” as this seems to be a simple r/r.

First question is about the dryer, I was hoping this was a simple install with a couple of screw. I just replaced the radiator due to a top crack and it was a pain for one person to do. My thought on replacing the dryer is to remove bottom screw, remove side screw, r/r. I’ve look up a couple of other makes/models with vq35 and that looks to be all that’s need, am I missing something? If removing the radiator is necessary I might skip it.

Second is the pag46 oil. You stated to remove oil from compress and dryer is this correct? I’ve read about measuring out the old compressor oil, and add just that amount but nothing about the dryer having oil and to account for that.

Lastly removing the compressor, did you remove the tire or fender well? Any simple tips on r/r this?

Thanks for your help. I should have it r/r this weekend and will be vacuum and refilling system sometime next week.... if everything goes smoothly(which it never does).

[Sstupid]

Thanks you for support. I got a couple of questions rafter reading your comments. Btw m35 07 and yes buyautopartskit.

I will be starting with the “expansion devise” as this seems to be a simple r/r.

First question is about the dryer, I was hoping this was a simple install with a couple of screw. I just replaced the radiator due to a top crack and it was a pain for one person to do. My thought on replacing the dryer is to remove bottom screw, remove side screw, r/r. I’ve look up a couple of other makes/models with vq35 and that looks to be all that’s need, am I missing something? If removing the radiator is necessary I might skip it.

Second is the pag46 oil. You stated to remove oil from compress and dryer is this correct? I’ve read about measuring out the old compressor oil, and add just that amount but nothing about the dryer having oil and to account for that.

Lastly removing the compressor, did you remove the tire or fender well? Any simple tips on r/r this?

Thanks for your help. I should have it r/r this weekend and will be vacuum and refilling system sometime next week.... if everything goes smoothly(which it never does).

First off, before we get into replacement of parts, your system is currently charged with Freon, and I can’t recommend venting R134 to atmosphere, so your first step will have to be getting the system discharged. This costs about $120 where I live. Removing any part of the system other than the compressor clutch, without discharging, can be very dangerous and bad for the environment. That being said, on to the questions.

I have an M45 and assume your radiator and condenser are the same. By the pics in the OEM parts catalog, they do look the same. There is a pressure switch at the top of the dryer, a band-clamp on the dryer which secures it to a bracket on the condenser, and two bolts/brackets holding the supply/return hard-lines. The band clamp,is easily accessible, but I had to remove my cooling fans, radiator, and bumper cover, then lift up on the condenser, to access the two bolts that hold the hard lines because they are inside slid down into the front radiator frame support and are inaccessible. I’ll see if I can get a pic. Radiator removal is no big deal. Don’t let that scare you off. You must replace the dryer if you are opening the system. It is a requirement. The expansion valve is up to you. They are usually fine to leave in, but you have to replace the dryer.

Every component of your AC system should have some PAG46 in it. It gets spread around during operation then settles in all of the components when not in use. The dryer will probably have a negligible amount in it but be sure to dump and measure to be sure.

Yes, dump and measure both compressors and only add back the amount that came out of the old compressor back into the new compressor.

The compressor comes out the bottom of the car on the M45. If it’s in the same location on the M35, Remove the bottom plastic pan that covers the underside of the motor, remove the tire, fender linings, and intake silencer (plastic tank behind the headlight bolted to the frame,) on the driver’s side, then you will have access to the four bolts that mount the compressor to the engine block and the two nuts that hold the suction and discharge hoses to the compressor. With all the fender linings out of the way, access is actually really good. I removed my radiator fans and radiator so I am unsure if this can be done without removal of those components on the M35, but you need to remove all that to get to the dryer anyway.

I think I took some pics during install. I’ll look and see what I have. Also, something to note: My compressor came without the studs that mount the suction and discharge lines. There were just bolt holes on the remanufactured compressor so I had to buy two bolts,from Lowe’s to get the lines mounted to the reman compressor.