AC not cooling after remained garaged for few months

[kapilamuni]

Hi,

My car, (BMW 525TDS 1997 model year), was not used during last few months due to Covid restrictions. Last week when I started it , noted that air coming through vents are slow & not enough cooling. Compressor engaging and both condensor fans working. Further investigation revealed taht RHS blower fan not working. Slowly during last few days, the AC became just plain air and compressor too stopped activating. Today, I removed the blower fan and brushes looked wor. But after cleaning the brushes with a sandpaper, it started running (anyway they need replacing soon). Checked all fuses and relays they are okay.

With AC gauges I got the following readings.

Outside temp - 32 C, humidity - 70-80%
Low side - 50 PSI
High side - 50 PSI

These are without compressor kicking in. Didn't try direct power to compressor fearing any damage.
Wonder, R134 leaked from seals as the car was not used few months.
Your advise sought to get it back to normal.
Thanks in advance.

[Cusser]

Have a shop recover the R134a and determine how low the systems is, then add correct amount plus UV dye. If AC performance is OK, shop will return to you for a few days or week, then you take it back in to have them find the leak, and repair the leak, etc.

NEVER add sealant or refrigerant containing sealant, that can readily ruin a system permanently...

[JohnHere]

Have a shop recover the R134a and determine how low the systems is, then add correct amount plus UV dye. If AC performance is OK, shop will return to you for a few days or week, then you take it back in to have them find the leak, and repair the leak, etc. NEVER add sealant or refrigerant containing sealant, that can readily ruin a system permanently...

This.

I would like to add:
Static pressures of 50 PSI at 32 degrees C (90 degrees F) suggest that the system is virtually empty of refrigerant. On a 1997 vehicle with possibly the original compressor (which wasn't stated), the compressor shaft seal is suspect, especially because: The car was setting for only a few months, the system was turned on, the compressor initially engaged and subsequently stopped--ostensibly because the refrigerant suddenly leaked out. This doesn't rule out a leak or leaks elsewhere, though.

The above is separate from the passenger-side blower issues you're having.

Didn't try direct power to compressor fearing any damage.

Glad you recognized the potential problem. Don't "jumper" the compressor.

[kapilamuni]

sadly, there are no AC recovery equipment with AC repair guys here and it's not mandatory too. When recharging they dont weigh the gas, instead they go by 'sweating suction' line.
About 3 years back I did the shaft seal with items purchased from this site sponsor, so dont think it's the seal. Anyway shown it to a repair guy and he says its the blocked 'expansion valve' and leaks from dried o-rings /the evaporator inside dash. If that's the case, I hate to let them remove the dash, they will certainly make it creacky and damage few other bits while at it.

I have a vac pump and I can vac it for an hour and see ?

[kapilamuni]

Oops!. sorry guyes, forgot to tell you all a very important observation.

Upto the time the compressor stopped, the expansion valve & the suction line was frosted. That's why I think the shop tech thinks the expansion valve is blocked. Is there a way to check the expansion valve?

[kapilamuni]

Hi,
Removed the expansion valve. Here are few pictures and I cant say whether its blocked or not.

Ooops, can't attach, too big.
Anyway, thought of replacing both TXV and the drier. Then vac and see any leaks.

[JohnHere]

Upto the time the compressor stopped, the expansion valve & the suction line was frosted. That's why I think the shop tech thinks the expansion valve is blocked. Is there a way to check the expansion valve?

Removed the expansion valve. Here are few pictures and I cant say whether its blocked or not. Ooops, can't attach, too big. Anyway, thought of replacing both TXV and the drier. Then vac and see any leaks.

Frost on the TXV and suction line suggests that the TXV is metering refrigerant into the evaporator. Did you notice any foreign material in the TXV when you removed it? Sometimes, in an older car like yours, the bag containing the desiccant in an original R/D disintegrates and sends desiccant beads downstream, where they would build up at the TXV and block it. This situation (or any blockage of the TXV) would also cause the low-pressure side of the system to show abnormally low gauge readings or even a negative pressure (vacuum).

There's really no reliable way to performance-test a TXV on the bench without specialized and costly equipment, which even Mobile Vehicle A/C shops aren't likely to have on hand. The only things you can do in the field is to examine the TXV closely for any physical damage to the valve itself, to the thin gas-charged sensing tube, to the thin equalizer tube if it has one, and for any debris that might be blocking the small internal orifice. From what you said, it sounds like this TXV isn't blocked.

The system definitely has a leak, though, and it could be anywhere...from a bad o-ring, to a pinhole in a corroded tube, to a bad pressure relief valve, and even the relatively new compressor shaft seal that just "decided" to leak as soon as the car was taken out of storage and the A/C system run. You can check for leakage at the evaporator without tearing the dash apart by electronically "sniffing" for the presence of refrigerant at the dash vents and at the condensate drip tube underneath the car. Traces of refrigerant found at either location indicate leakage from the evaporator itself (usually due to corrosion) or from a leaking joint.

Your plan to evacuate the system to determine whether it holds vacuum is fine, but it's not a definitive test by any means. Bear in mind that a system that leaks under pressure might not leak under vacuum, and vice-versa. I would do whatever is necessary to find and repair the leak(s) first, then replace the R/D, draw a deep vacuum on it again for at least a couple of hours, double-check that the vacuum holds, then recharge precisely to specs.

Sadly, there are no AC recovery equipment with AC repair guys here and it's not mandatory too. When recharging they dont weigh the gas, instead they go by 'sweating suction' line.

I don't have the A/C specs for your vehicle, but the only reliable way is to recharge it by net weight of the refrigerant and by fluid ounces of the PAG oil. Look for an under-hood decal that provides these specs.

[kapilamuni]

Thanks.
Removed both TXV and RD. The TXV looks clean and not blocked(?). But when I removed the line to RD from condensor there was a big hiss, indicating blocked RD, I guess.
Now to buy these two items. What it means by the tonnage on the TXV, (I have seen on ebay TXVs)? The one I removed has no markings on it. The parts shops do is to match item by external looks/dimensions, so knowing what to buy will help.
The car's stcker says "R134a 1100+/- 50 gm , ND 8 oil ".
To charge it by weight I will have to goto the dealer. It's expensive and they will want to replace all the parts in the AC system first.

[kapilamuni]

Insatlled new RD and TXV (1.5 Ton ?). Vaccd and held for 1 hr. Put 20ml of ND 8 oil and charged till sweating from suction line.
The fiugures are;
Ext temp - 29 C, humidity 90% (from weather guys)
Low side - 28 , High side - 170 PSI
RPM - 1600

Interior temp came down to 11 C after a while. This is with all doors open and blower on full speed.
However didnt notice the compressor cycling. It appears to run continously ?

Anyway hope the interior temp will hold on hotter days to come. Fingers crossed.

Thanks everyone.

[JohnHere]

Removed both TXV and RD. The TXV looks clean and not blocked(?). But when I removed the line to RD from condensor there was a big hiss, indicating blocked RD, I guess.

Sounds like you found the blockage problem, and hopefully, the leak(s). It would be interesting to cut open the old R/D, examine the insides, and see where and what the problem was.

What it means by the tonnage on the TXV, (I have seen on ebay TXVs)? The one I removed has no markings on it. The parts shops do is to match item by external looks/dimensions, so knowing what to buy will help.

Tonnage and superheat aren't normally paid much attention to on MVAC systems because of the continuously varying system operating parameters. If I need to replace a TXV for whatever reason, I look for an OEM part for a given vehicle. Problems with aftermarket TXV's have shown up in the past.

The car's stcker says "R134a 1100+/- 50 gm , ND 8 oil ".
To charge it by weight I will have to goto the dealer. It's expensive and they will want to replace all the parts in the AC system first.

That's about 40 ounces net weight or 2.5 pounds of refrigerant. Instead of weighing-in the charge, you could approximate the optimum amount by charging three full 12-ounce cans into the system plus an estimated four more ounces from a fourth can. It's not the preferred way of charging, but it will at least get you close.

Insatlled new RD and TXV (1.5 Ton ?). Vaccd and held for 1 hr. Put 20ml of ND 8 oil and charged till sweating from suction line.
The fiugures are;
Ext temp - 29 C, humidity 90% (from weather guys)
Low side - 28 , High side - 170 PSI
RPM - 1600

Sounds like you're on the right track with the refrigerant amount, and the make-up amount of oil (0.6 of an ounce) added for the new R/D sounds good as well. But with a vent temp a mediocre 11C or 52F, a high-side reading of 170 PSI, at an ambient temperature of only 29C or 84F, it still seems to be a bit undercharged. I would add more refrigerant, 25 grams or about one ounce at a time, while monitoring the high-side pressure and the vent temps (not easy to do for one person, I know). Presuming approximately the same ambient temp as before, once you get the high side up to around 200 PSI and the vent temps in the 7C or mid-40F range, you will have the refrigerant charge just about right.

However didnt notice the compressor cycling. It appears to run continously ?

With your testing parameters placing a high heat load on the system, the compressor will run continuously. Once the heat load drops, the compressor will cycle as expected to prevent the evaporator from icing-up.

Anyway hope the interior temp will hold on hotter days to come. Fingers crossed.

Please do come back and let us know how it performs.