A/C makes loud noise (rpm-related)

[ILoveMPower]

When I'm driving with my A/C on (err, the snowflake :P), I'll sometimes notice a kind of grinding/buzzing noise coming from the engine bay. Now I understand the ac has to make SOME kind of noise, but this noise doesn't make the sound of BMW refinement.

If I have the radio off, and notice the noise while cruising at say 2.5-3k rpms, as soon as I push the clutch in the noise immediately stops (or at least grows too quiet for me to hear).

Any help or input is much appreciated!

[BillionPa]

compressor bearings.

there is a clutch that disconnects the compressor from the drive belt pully when its off, so the sound is inside the compressor.

[ILoveMPower]

compressor bearings.

there is a clutch that disconnects the compressor from the drive belt pully when its off, so the sound is inside the compressor.

how difficult is it to replace these? also approx how much $$?

[BillionPa]

i dont know if they are fixable, usually the compressor is replaced.

[joshua43214]

The compressor can make noise if not properly charge too, I would check the bearings first, the clutch assembly can be replaced without dischargeing the AC, but most folks replace the whole compressor since its often not much more.

[BillionPa]

indeed, low charge, which contains the lubrication oil, is a major factor in AC componenet damage.

[ILoveMPower]

so how much can i expect to pay to get my A/c working properly again?

[joshua43214]

so how much can i expect to pay to get my A/c working properly again?

For evac and recharge, expect to pay 1-1.5 huors labor and $45.00 or so a pound for R134a. So budget about $250.00 and you might get change. Every shop has its own protocol for this job, some will charge .5hr and just squirt in the stuff, most repudable places will do a fast sniffer check, try to spot any obviouse leaks and add some dye, so the any leak can be pinned down for sure at a later date. The dealer is as good as any place for this, they will charge more per labor hour, but you have the best chance of getting a competant person on the machine. They will be competive on the cost of R134a and might have a summer special running.

[Bill R.]

price for a case of 134a at costco or sams club right now is about 48 a case or 4 dollars a 12 ounce can. R12 is considerably higher than that.





For evac and recharge, expect to pay 1-1.5 huors labor and $45.00 or so a pound for R134a. So budget about $250.00 and you might get change. Every shop has its own protocol for this job, some will charge .5hr and just squirt in the stuff, most repudable places will do a fast sniffer check, try to spot any obviouse leaks and add some dye, so the any leak can be pinned down for sure at a later date. The dealer is as good as any place for this, they will charge more per labor hour, but you have the best chance of getting a competant person on the machine. They will be competive on the cost of R134a and might have a summer special running.

[joshua43214]

=), ya but most shops will not allow you to bring your own parts, and no one wants to be sucking a customers refrigerant out of those sucky little cans when they can just use the big bottle they got from NAPA that is strapped to the machine. I would always demand more time on an AC job if someone dumped those cans on me.

In my experience, folks that quibble over the price of an evac and recharge are the same folks that want free or cheap estimates so they can go home and do it themselves on other repairs. Often the same folks that want Saturday service or want to come after 5:00 PM, basicaly the worst customers, They go straight to the bottom of my priority sheet and they get the service performed when I finish the work that is feeding my family.

[Bill R.]

price of an evac and recharge but i do have many who want to supply their own refrigerant. I have a number of customers who bought r12 30lb er's back before the ban went into place upon my advise. They bought these for an average price of 70 to 130 back then. They bring their bottle to me whenever they need some work on whatever r12 using cars they still have.
i have a couple who no longer have any cars that take 12 and they have either given or sold their remaining r12 to me. A good number of them still have r12 cars though and it doesn't bother me in the least if they supply their own refrigerant.
Since i don't mark up parts anyway theirs no reason for me to care if they supply their own. Usually i prefer since it saves me the trouble of getting it for them.




=), ya but most shops will not allow you to bring your own parts, and no one wants to be sucking a customers refrigerant out of those sucky little cans when they can just use the big bottle they got from NAPA that is strapped to the machine. I would always demand more time on an AC job if someone dumped those cans on me.

In my experience, folks that quibble over the price of an evac and recharge are the same folks that want free or cheap estimates so they can go home and do it themselves on other repairs. Often the same folks that want Saturday service or want to come after 5:00 PM, basicaly the worst customers, They go straight to the bottom of my priority sheet and they get the service performed when I finish the work that is feeding my family.

[High Compression II]

price of an evac and recharge but i do have many who want to supply their own refrigerant. I have a number of customers who bought r12 30lb er's back before the ban went into place upon my advise. They bought these for an average price of 70 to 130 back then. They bring their bottle to me whenever they need some work on whatever r12 using cars they still have.
i have a couple who no longer have any cars that take 12 and they have either given or sold their remaining r12 to me. A good number of them still have r12 cars though and it doesn't bother me in the least if they supply their own refrigerant.
Since i don't mark up parts anyway theirs no reason for me to care if they supply their own. Usually i prefer since it saves me the trouble of getting it for them.



A recent spell of hot (for the UK anyway....) prompted me to fix my A/C on my 525TDs, especially as I cant open the windows, but thats another story!...

The same (or very nearly the same) system is fitted to most E34 cars.

I diagnosed a compressor leak as I bought one of those el-cheapo cans of 're-charge' from a local motor-shop. Followed the instructions and emptied the lot into the system with engine running....Hence I didnt hear the leakage--What a con that was!...

To cut a long story short..The 'O' ring seals of the compressor main caseing were leaking...

OK, Compressor off, and strip down...There are three main-case 'O' rings which harden with age and temp. These were replaced. The compressor is the Nippon-Denso 10PA17 compressor which is a 'swash'-plate design with five double-acting pistons arranged in a circular pattern round the central 'swash-plate' The shaft is supported by needle-roller-bearings and has needle roller thrust-races at each end.

A great piece of precision engineering with Teflon coated pistons and precision 'reed'-valves The shaft is sealed by a specialised double-lipped type seal Great care and clenliness is needed when working inside the compressor as moisture and dirt of any sort can cause issues down the road--Im used to working on Diesel injection pumps and systems, so this is 'normal' practice to keep everything as clean as possible......

The whole assembly is lubricated by a specialised oil known as PAG 46 or PAG 100 if its an old noisy pump is recommended...
PAG stands for Poly-Alkyl-Glycol, a lubricant rather similar in some ways to brake-fluid..Its Highly Hygroscopic,--Absorbs Water.... If the system is opened to air for more than an hour to two, it should be replaced....

I repaired my compressor, and re-fitted only to find my condenser was also leaking, so that was a special-order, as the TDs Intercooler makes the space needed for the condenser smaller hence one from any other E34 (which allegedly are all the same) wouldnt fit mine as they are 3 inches taller

It came in and was fitted...

Now how to 'gas-up'.....

By the 'book' the system should be flushed through with spirit solvents and the reciever-dryer replaced.

I could afford no such luxury, as I had already spent out on the condenser, so got hold of a reciever-dryer from a defunct E34, which still had a small amount of gas-pressure present, sealed it imediatly it was removed from the donor car.

Using an old compressor from a refrigerator, I pumped down the replacement reciever-dryer to near-vacuum and left overnight to dry any moisture, I also drained its remaining oil of 20mL

Fresh PAG 100 oil was installed in the compressor, according to TIS, 160mL plus 30mL was needed for the system, allowing for some in each unchanged component I put 160mL in the dry compressor, and allowed 15mL for the reciever-dryer bringing total up to 175mL. (The evaporator will still contain some little amount of oil)

All system components were installed and 'O' rings replaced as needed on every joint that had been disturbed.

My local refrigeration supply house supplied the R134A gas in 1Kg 'aerosol-type' cans, with an adaptor and tap. It was simple work to make up the plumbing and 'T' piece to connect the old fridge compressor to use as vac-pump and a few taps and a guage for good measure. The filling adaptor from the 'el-cheapo' re-charge was attached to the plumbing for attachment to the car low-pressure port.

I pumped air into the system first from the fridge compressor, via a drier I made up, to check for leaks. I applied 100 PSI, and painted all joints with soap/water Left to see if there was any pressure loss,--None,...Great, No leaks....

I turned round the fridge compressor and vacuumed the system for an hour. I then allowed a Little R134A, just enough to equalise pressure to atmospheric, then re-vacuumed for two hours.

TIS gives the R134A quantity as 1450 grams for 'flat' tube condenser, and 1550 for 'round' tube condenser for the TDs...I had a round-tube type.

My bottles of R134A were 1Kg each, so I first allowed as much as would go in unaided by holding the bottle upside-down suspended on the bonnet-catch.

It became obvious that only around a quarter had entered the system. I had to start the car, and allow the A/C to reduce the pressure on the 'low-pressure' side to allow more gas to enter. This done, it emptied the bottle in a few mins.

Next I measured the weight of the fresh unopened bottle, which was 1150 grams approx.--I needed to get to 600 grams for a full system. This was the hard-bit as I had to disconnect it each time to check its weight, in the end, I put around 120 grams too much in, but it doesnt seem to make much difference to its 'low' running pressure, and has now been working for nearly two weeks faultlessly...(apart from the drive-belt, which was worn slipping initially...Its since been replaced....)

The whole job including the 'O' rings, PAG 100, plumbing and guage, (Old fridge compressor was free from a friend..) condenser and gas cost me around 160 stirling, maybe around 300 dollars, and a great deal of self-satisfaction, as I had been quoted nearly 500 stirling, or around 1000 dollars to fix just the compressor! The Condenser cost 96 Stirling alone...