e46 Intermitent AC has full charge

[forrestohyea]

My 2000 e46 323i just started to blow hot air and then cold air, and back and forth! AC has a charge of 50psi. I popped the hood and the ac clutch will disingauge for about 3 to 7 seconds and rein-gauge for about the same time??? What could the problem be? Thank you.

[slvrXI]

clutch switches like that its normal... What do mean charge of 50 psi? Proper AC charges are measured in weight.

50psi on the high side? low side? If its 50 psi on the low side, it is definitely over charged. If it is 50psi on the high side, then its way undercharged.

Heres what you need to do... Recover any r134 that's in the system. Evacuate the system for at least 15 minutes. Perform a vacuum test for at least 10 minutes and make sure it does not lose ANY in/HG. Inject about 1 oz of PAG oil, then charge 1.65lbs EXACTLY THAT AMOUNT. NO MORE NO LESS. (unless your AC tag under the hood says differently.)

After this is completed, come here with any further questions you have regaurding the AC.

Also, if you can not perform this procedure to the exact step, take it to someone who can. There are very strict Federal guidlines on handleing Refridgerant, and it is legally required that you are certified before performing any type of refill/recharge work on any AC system.

Edit just a tip... When it is overcharged the AC will work fine untill the pressure gets too high, then the system will cut out untill pressure drops to a safe level. Any system that is overcharged will never cool the car as well as a properly charged system.

[danewilson77]

clutch switches like that its normal... What do mean charge of 50 psi? Proper AC charges are measured in weight.

50psi on the high side? low side? If its 50 psi on the low side, it is definitely over charged. If it is 50psi on the high side, then its way undercharged.

Heres what you need to do... Recover any r134 that's in the system. Evacuate the system for at least 15 minutes. Perform a vacuum test for at least 10 minutes and make sure it does not lose ANY in/HG. Inject about 1 oz of PAG oil, then charge 1.65lbs EXACTLY THAT AMOUNT. NO MORE NO LESS. (unless your AC tag under the hood says differently.)

After this is completed, come here with any further questions you have regaurding the AC.

Also, if you can not perform this procedure to the exact step, take it to someone who can. There are very strict Federal guidlines on handleing Refridgerant, and it is legally required that you are certified before performing any type of refill/recharge work on any AC system.

Edit just a tip... When it is overcharged the AC will work fine untill the pressure gets too high, then the system will cut out untill pressure drops to a safe level. Any system that is overcharged will never cool the car as well as a properly charged system.

yeah, I am sure he has all of the gear to evacualte and pull a vacuum on his ride......lolz....


Cmon man....he's gonna have to take it in. Got any cost estimate for him to take it to a non BMW shop?

slvrXI FTW!!!!!

[slvrXI]

I'd do it for like 20 bucks... since it takes no effort, you can do other things while the machine is sucking it out, you just gotta hit buttons every few minutes. Or you can just sit there and watch it, but then you can't make money on the brakes that are in the stall next to you.

lol if anyone charges you more than 100, they are full of it. Most shops will charge around 65-85. Also some shops will tell you that there is a leak and they need to replace a part and its gonna cost you 100000 dollars. When this happens, ask to see the leak.

They either used a dye and UV light to find it, or they use an electronic leak detector which senses the gas leaking and beeps at you. Both ways are very easy to show the customer...

If there is in fact a leak, then the shop may refuse to recharge it without repairing the leak... Which is perfectly acceptable since they could get in a lot of trouble. Tell them thanks for the time and go somewhere else. Most leaks are very minor and they will not fully leak out untill the Hot season is well over. So find a shop that will do a quick recharge for ya and all will be well.


Good luck and make sure you shop around, some people charge you to just hook up the machine, and some just charge you a standard refill, and some will charge you by the pound.

SHOP AROUND and find the deal.

Make sure they use a real AC machine there tho, and not just the can from autozone... I know a couple shops that do that.

phew... end rant.

[forrestohyea]

Here are some pics. I believe it is hooked up to the low side and it reads 45psi. Yea I know its the can from autozone. I will just have to take it in to a shop to make sure it has the right charge i guess. Note i did not have to add any of this stuff but I did put about 1psi in (about 1/16th of a can)

[slvrXI]

EZ CHILL lol, thats too funny. Is that with the car running?

And yes that is the low side.

[forrestohyea]

Oh, and there are no leaks. at least not for the last 40k miles that I have owned it.

Thank you.

P.S. Yes the car is running with ac on full blast compressor engaged.

[slvrXI]

ok, well that reading could mean a lot of stuff. It could mean that there is a clog/restriction in the line, there is insufficient air flow going across the condenser, the evap is freezing up... OR its just over charged. Best bet is to take it to a shop... Just make sure you trust the guys or know someone over ther, they will help you charge it even if its leaking...

Good luck.

[danewilson77]

I'd do it for like 20 bucks... since it takes no effort, you can do other things while the machine is sucking it out, you just gotta hit buttons every few minutes. Or you can just sit there and watch it, but then you can't make money on the brakes that are in the stall next to you.

lol if anyone charges you more than 100, they are full of it. Most shops will charge around 65-85. Also some shops will tell you that there is a leak and they need to replace a part and its gonna cost you 100000 dollars. When this happens, ask to see the leak.

They either used a dye and UV light to find it, or they use an electronic leak detector which senses the gas leaking and beeps at you. Both ways are very easy to show the customer...

If there is in fact a leak, then the shop may refuse to recharge it without repairing the leak... Which is perfectly acceptable since they could get in a lot of trouble. Tell them thanks for the time and go somewhere else. Most leaks are very minor and they will not fully leak out untill the Hot season is well over. So find a shop that will do a quick recharge for ya and all will be well.


Good luck and make sure you shop around, some people charge you to just hook up the machine, and some just charge you a standard refill, and some will charge you by the pound.

SHOP AROUND and find the deal.

Make sure they use a real AC machine there tho, and not just the can from autozone... I know a couple shops that do that.

phew... end rant.

Great info for all...thanks

[Phillips0417]

First of all, duuuuude, clean your engine bay..that makes me so sad!!

SlvrXI is correct, the system needs to be properly evacuated and and held under vacuum to check for leaks, all shops do it to properly diagnose; if it doesn't hold a vacuum, there is a leak and dye is injected to locate.

Another thing you should look at is your fan, the fan should circulate with the compressor. Try hosing your condenser down with a garden hose while charging too, I've heard that from many old timers.

The high/low pressure switches are there for a reason, to keep the compressor from burning up. Too much pressure or too little pressure won't allow the compressor to run for very long if at all.

[slvrXI]

First of all, duuuuude, clean your engine bay..that makes me so sad!!

SlvrXI is correct, the system needs to be properly evacuated and and held under vacuum to check for leaks, all shops do it to properly diagnose; if it doesn't hold a vacuum, there is a leak and dye is injected to locate.

Another thing you should look at is your fan, the fan should circulate with the compressor. Try hosing your condenser down with a garden hose while charging too, I've heard that from many old timers.

The high/low pressure switches are there for a reason, to keep the compressor from burning up. Too much pressure or too little pressure won't allow the compressor to run for very long if at all.

Lol the garden hose idea... I do that all the time... cold water cools a lot better than warm air, haha... Works great for the radiator as well.

I think since his low side is at 50psi, when it should be lower than that, then his high side must be WAY up there, causing the high pressure switch to kill the compressor.

[Phillips0417]

50 psi is definitely too high, it should be in the 25-35 range, some a little higher, but definitely not 50...I think high side is typically 250-400(?) range, again, varies along with ambient temperature too.

Found this from another site, may be worthwhile to read, gives a little insight to what goes on with the system and how it works and cools.
http://www.aircondition.com/wwwboard/current/44954.html

[slvrXI]

You are correct... I charged a ford windstar today (after replacing the schrader valve on the high side fitting that was leaking) It had dual zone AC and took a whopping 3.5lbs. It blew cold as ice, (about 55 degrees) yet the high side at idle was sitting at around 150... then when I revved it up I could get it to 350. Low side ranged from 20-40.

Something else is screwed up on the system, but the car is 11 years old and falling apart so I charged it, and let em go... They were happy, I was happy... And they didnt spend 400 dollars to have cold AC this year.

I love how that website stresses "REMOVES HEAT" because thats exactly what it is doing... I remember that was a test question...

The purpose of the evaporator in an Air Conditioning System is to...
A. Cool the air
B. Humidify the air
C. Dry the air
D. Remove the heat

[Phillips0417]

wow 3.5lbs...

Hey, some people will pay every year to have their systems charged, even if it's just for the summer as I'm sure you know...keeps ya in business too!

[slvrXI]

wow 3.5lbs...

Hey, some people will pay every year to have their systems charged, even if it's just for the summer as I'm sure you know...keeps ya in business too!

Well this van that came in... It was rusty and it sounded like it was about to fall apart. So if the vehicle is in that bad of condition... why try to sell something else to them?? I think the AC will outlast the van in this situation.

[Phillips0417]

haha so true...

[forrestohyea]

Problem Fixed!!! Did I mention I love my BMW and yes Phillips0174 I will clean my engine bay, it makes me sad to look at the pics. ------------- Problem---------It was overcharged! --------I never had the problem before because I had never been in 112 degree weather before which caused the already high pressure in the system to rise a very small amount more, then triggering the high pressure switch.(Thanks silvrXI) I have never had this system charged or checked since I have owned it. I guess I now know it doesn't leak. lol

Thank You everyone for your fast responses :---)

[Phillips0417]

Good for you! Now you're cool

[slvrXI]

Well I did just this today... And here is what I came up with, Sorry the photos are chitty, it was with my BB and that camera sucks more and more every day.

Looks like around 30 for the low side, and just under 200 for the high side...

And yes that vent temp gauge reads 45 f**kin degrees... Ballin.













To the OP... Where did you take your car for the proper charge? And how much did they charge you? It should have been free since they took some of your refidgerant.. lol.

[slvrXI]

...

[slvrXI]

Answer me damnit!

[mecartneys]

Old thread, I know. The A/C works perfectly then no longer cools. If I make every adjustment to the temperature, Auto, fan speed - makes no difference. If it's left alone it will start cooling again. No rhyme nor reason. Correctly charged, no leaks, compressor cuts on and off. Any ideas?