[Jagaer]

I live in Canada, and have had my car in storage for a couple of years. We had our first real heat this past week (>25C) and I unfortunately learned that my A/C is weak/non-existant.

Despite owning an B5 A4 that was 18 years old, and a 13 yr old Tiguan - Neither required any work done to their A/C in the entire time I owned them.

It looks to me like the car might just be a bit low on refrigerant, posting it here for a second opinion before getting it checked out.

• After leaving the car in the garage all night. Car Off.
• 3.0 Bar seems right.

• Started the car, set temp to 16C and fan to Mid/"4".
• Evap immediately started to drop and pressure started to rise.

• Car running for 5 minutes. The Evap temperature dropped down to 16C approx 1 min after starting the car, and then the temperature gradually starting to rise again.
• Pressure bounced between 9.5 and 10.0 bar.
• Vent temp was stable at 24C (Drop of 2C from initial)

• Immediately after turning the car off again.
• Pressure dropped quickly.

A couple of notes:
1. I don't have A/C gauges, since I've never needed them before. So ISTA was the best I could do right now.
2. You cannot buy R134A in Canada, only licensed dealers are authorized to refill. You can buy R12 in a store, but I'd prefer not to mix coolants.

[TunafishE93]

You really can't go off of pressure to see if low or high on refrigerant. This is why the specs are in lbs of refrigerant and not psi of the system. The psi can tell you if you have a leak and if your compressor is working but that limits it there.

I would get refrigerant evacuated and then filled to specs. This would tell you if you were low, if you are in specs for being low and now you will know for sure that you are in specs. Doing it by pressure you will never know for sure.

Not sure what it costs up there but in the States I paid $150 and that is on the high side. I do all my work on the car and this is one thing I can't do, that and alignment.

[marvinstockman]

You may need R134a, as three bar, 45 psi, with system, off is probably a little low.

Now with the high pressure side at 10 bar (~150 psi), you should be getting some cooling, and may have a stuck internal flapper. Also, you're evaporator should be cold.

With engine running and AC on, check to see if the return line is cold. The high pressure line should be hot, and the low pressure cold.

[lookalikehuuh]

Originally Posted by Jagaer

You cannot buy R134A in Canada, only licensed dealers are authorized to refill. You can buy R12 in a store, but I'd prefer not to mix coolants.

So
#1 you should not be doing A/C work yourself, in order to properly recharge an A/C unit you must safely evacuate the system and place a vacuum using a pump on the system to ensure all moisture has been removed. Removing the existing refrigerant requires specialized equipment to be done safely. DO NOT VENT TO ATMOSPHERE!!

#2 R12 should not be used in systems designed for R134a unless you want to heavily damage the air conditioning system.

If you are truly losing refrigerant then you need to find the leak using an UV light and glasses, have the system properly evacuated, fix the leak, place a vacuum on the system and confirm it holds the vacuum for an extended period of time and then have the system recharged with R134a with the proper amount of refrigerant and oil.

[Jagaer]

TunafishE93 marvinstockman

I very much appreciate the useful info & quick reply.

1. After a couple of minutes the high side is warm to the touch, and the low side is cooler than ambient (but not cold)
2. I used ISTA to monitor the flaps, and they are all moving, so unless one of the flaps isn't monitored by diagnostics, it looks like they are all moving.

It wouldn't surprise me if it is a bit low on refrigerant, as the A/C has likely not been serviced for the past 11 years. (Probably doesn't help that it was in storage for the past 3 years, not driven)

I'll call around for a couple of quotes. The first place I called quoted $300 + 13% tax for just the evac + fill (Fill was $5 / 100g of R134a), no diagnostics or other service.

[mainbearing]

3 bars at 25C is low. You should see something like 5 bars. And at 30C ambient you should see around 14-15 bars while running at 2000 rpms.

That price in Canada is like 3x the US, but that would be the proper way to service the system, as you have to make sure there's not just whole bunch of air in the system. How about driving south of the border? LOL!

Here was one member with slightly low charge as well. At 9 bars, the evap was at 2C. Therefore you might not just want to put refrigerant in there without evac.

Also, as you found out, BMWs are not as reliable as Audi/VWs.

https://www.e90post.com/forums/showthread.php?t=1626280

[gbalthrop]

1) Your data DOES show QUITE LOW Refrigerant Pressure after system has sat without engine running for several hours. Pressure on High Side (measured by Refrigerant Pressure Sensor at 3 bar) would be at "Equilibrium" with or equal to "Low Side" pressure as would be measured by a gauge attached to Low Port near Brake Fluid Reservoir.

2) If that Refrigerant Pressure got much lower than 3 bar (43.5 PSI) the Compressor Valve would NOT operate (to prevent damage from lack of refrigeration oil / PAG oil being circulated to lubricate compressor.

3) Refrigerant Pressure at Equilibrium SHOULD be at 5 to 6 bar to get proper cooling. Whether or NOT the refrigeration system is operating properly can be determined by simply looking at (a) Refrigerant Pressure (High Side Pressure which indicates that Compressor is "Pumping"), and (b) Evaporator Temp, which indicates if the Evaporator/ Cooling Coil is getting cold enough to cool the air flowing through it sufficiently.

4) Evaporator Temp should be 10C or lower to get proper cooling, and temperatures approaching 0C are seen in some Outside/ Ambient Temp and Interior Temp situations. Your Evaporator Temps are 18C or 19C when Outside Temp is 21-22C. When the weather gets HOT, you will have virtually NO Cooling.

5) It's a shame CA doesn't allow the sale of R-134a to individuals. In the US, we can buy a 12-oz can of R-134a in Walmart for $5. What leaks out of our cars blows into CA when the wind is from the South.

6) Also, there are fire problems with 12A Refrigerant (Propane/Isobutane). Can you say "BlowTorch"?

7) Folks who confuse 12A with R-12, should read this:
https://en.wikipedia.org/wiki/HC-12a

8) Those of us in US where R-134a cans are available, and who have either Manifold Gauge set, or Can Tap with Low Side Gauge and INPA/ ISTA to read Refrigerant Pressure and Evaporator and Outside Temps, CAN/ $HOULD learn how to diagnose LOW Refrigerant Pressure, and HOW to use gauge readings, along with Temp readings, to properly charge the system. You do NOT need to $pend Hundred$ to evacuate & recharge by weight. Here is an example Pressure/ Temp Chart:
https://www.acprocold.com/faq/r-134a...ressure-chart/

9) Until the "Ozone protecting" legislation of the early 90's, shops and individuals (like me ;-) charge systems by Pressure/Temp charts for R-12 (or R-22 on home systems). There is NO Reason an individual CANNOT do that today with R-134a systems. I have done that MANY times in the last 20+ years, and NEVER had an issue with a compressor or other component in the refrigeration system. HOWEVER, the shops are required by law to do it a certain way, and have expensive equipment and licensing/ training requirements per government mandate. OF COURSE they want you to ONLY rely on them.

10) Environmental impact of refrigerants (including R-134a) is NOT a Hoax. So what's a fellow to do. Begin by learning the FACTS instead of repeating Web Legend, and make your OWN, INFORMED decision.
George

[TunafishE93]

Just because someone does something for 20+ years doesnt make it the correct way. Plus BMW A/C if very small range of refrigerate to be in range compared to domestic vehicles. One can do as they please but the specs are not in PSI.

I been changing spark plugs for 20 plus year but never did it right, i tighten to feel and never had an issue. The one time i torqued a plug it broke and i had a time getting it out of the head. Moral of the story sometimes winging it is good, other times not good.

[marvinstockman]

Tunafish, AC is AC, whether it is German, Japanese, Korean, or America/Canadian. Remember, they mostly are using R134a, which sets the operational parameters.

That being said, my '98 had a somewhat crappy AC, as does my 2011 328i. My 2003 Dodge Caravan had an ice cold system, as does my 2010 Honda Odyssey.

[gbalthrop]

Originally Posted by TunafishE93

... doesnt make it the correct way...

Who said there is ONE CORRECT WAY / My Way or the Highway? That's the WHOLE point.

There are NOW, and have been over the ~ 65 to 70 years that A/C systems have been installed in motor vehicles, DIFFERENT WAYS to charge a refrigeration system. In the early days there was NO public concern for release of R-12 Refrigerant into the atmosphere, and individuals, or even paid shops, could vent refrigerant and start over by weight if they wanted.

Charging by weight is a concept ANYONE can understand, and ANY "dummy" or tech can follow. If you have a scale or system for accurately measuring the WEIGHT of refrigerant added you can just pump it in and be done with it. NO "putzing" with temperatures or pressures.

You get the added bonus of using a vacuum pump for 30 minutes or more to draw a vacuum, remove moisture that reduces cooling capability of the system and makes internal corrosion more likely. Let it sit another 30 minutes to make sure it doesn't leak (lose Vacuum), and you have covered ALL the bases (except PAG Oil content).

With the advent of Federal Government regulation of shop refrigeration system repair, MANY people (perhaps you ;-) have determined that they should NEVER touch their Refrigeration system. Look at Bentley Manual, Section 640 related to "Heating and Air-Conditioning".

Other than a statement on the FIRST page of that Section, that "Strict regulations govern the handling and disposal of automotive refrigerant" (WITHOUT saying anything about WHAT those regulations provide, their Intent, or to WHOM they apply ;-) and a restatement of the what the underhood label says about refrigerant capacity (590 grams +/- 10 grams), there is ONLY a diagram of the Refrigeration system components on 1/3 of a page, 640-22 (p.875 of pdf).

Right-wingers are supposed to resist "BIG Government" interference with their guns, states rights, and all that stuff. Suggesting you cannot Safely, Effectively, and LAWFULLY handle automotive refrigerant, and have to pay someone else HUNDRED$ $$$ to do something YOU can do yourself with INPA or ISTA, a $12 Can Tap with Gauge, and a $5 can of R-134a from Walmart? What's WRONG with this picture?

The bulk of the provisions in Federal Law regulating R-134a apply to shops, dealers and manufacturers, and NOT to individual owners. The ONLY possible violation of either the wording or intent/ purpose of the Act an individual owner, charging his system, can commit is discharge of R-134a into the atmosphere. Criminal Prosecution requires proof of "Criminal Intent". Any lawyer who has ever tried a case understands the "Problems" that requirement presents to a prosecutor.

For "Lefties" who are concerned about the environment, IF you use care in attaching and disconnecting the quick connect port(s), you won't discharge any more than a pro does. So don't make your decision on what to "Do Yourself" a matter of "Politics".
George

[Jagaer]

Final Update:

Turns out it was 100g short on refrigerant. I did get the shop to add dye to the recharge, just to make it a bit easier to check/troubleshoot if it acts up in the future.

Total cost:
- 1hr labour @ $135
- R134A Recharge @ $43

Subtotal: $178
Total (Incl 13% Tax) $202