Page 1 of 2

Replaced compressor, failed again 9 days later. Advice sought

Posted: Mon May 14, 2018 11:40 pm
by hcanning
Hi folks,

I do enjoy working on cars but AC really is not my area of expertise (or ability, since I don't have the tools to work with the gas!).

The problem is with my girlfriend's car, a 2007 Toyota Auris. A while back, we noticed that the AC no longer worked. It gets used all year round with the climate control set to 'auto' so we thought it odd.

I had the AC system regassed, which did not help. Their printout showed that it did only have 220g gas in the system, and they filled with 440g.

I managed to diagnose the issue as a faulty compressor - it's a variable displacement type and it appeared that the fail-safe lugs on the pulley had "activated" probably due to internal seizure.

I purchased a new compressor and had it fitted by a mobile air conditioning specialist last Saturday (May 5). All was well, and it blew nice and cold. The AC guy did only manage to evacuate 290g out of the 440 previously put in 2 weeks ago though.

Fast forward to yesterday (Monday May 14) and it stopped working suddenly whilst driving.

Again, it appears that the new compressor has failed in the same way!

There were no leaks according to the vacuum test that the AC guy did, although this was by no means an in-depth test.

Nothing else was replaced, only the compressor - perhaps this is my problem?

The condenser looks rather old and "well-used", but it still appeared to cool quite happily.

I did notice a few days ago in the hot weather that the cooling fan (and presumably the compressor) appeared to by cycling on and off quite quickly - every 10-15 seconds perhaps at one point. Again, still nice and cold in the car.

Could it be that there is a leak which is causing the compressor to fail before the pressure switch detects low enough pressure to shut the system down? Would the fact that it could potentially have lost a couple of hundred grams of gas in a couple of weeks still not show up on a vacuum leak test?

Any advice would be greatly appreciated. Thank you.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Tue May 15, 2018 10:13 am
by JohnHere
You mentioned that the first time the shop recovered the charge, only 220 g (7.8 oz) came out. That's a little less than half the refrigerant charge (450 g, 15.9 oz) the specs for your vehicle call for. So it was quite low to begin with. On replacement of the compressor (but perhaps not the receiver/dryer and condenser), the shop recovered 290 g (10.2 oz) after only two weeks out of the 440 g (15.5 oz) they put in. That amount of refrigerant loss in such a short period of time suggests a sizable leak (or leaks) somewhere.
In addition, even though the system held a vacuum doesn't mean it's leak free. Often, a system will leak under pressure while showing no signs of vacuum loss.
With all that being said, it's possible that some or most of the oil leaked out with the refrigerant causing the original compressor to fail. I also wonder whether the new compressor came with any oil in it, and if not, whether the shop replenished the oil with the proper amount and type.
According to the specs I found, your car calls for only 450 g (15.9 oz, a little less than a pound) of R134a, and only 90 g (3.2 oz) of PAG46 (ND-8) oil. Those are both very small amounts, particularly the oil. So on a percentage scale, only an ounce or two of oil loss would most likely starve the new compressor for oil and cause it to fail.
If the problem points to oil starvation destroying the compressor, you'll have to replace the compressor again (you'll have to do so in any case), along with the condenser, which among other things serves as a filter that catches any debris thrown off by the two now-failed compressors. The receiver/dryer should also be replaced.
After any leaks are repaired, the components replaced, and verifying that the proper amount and type of oil is installed in the system, an evacuation and recharge should have you driving in cool comfort.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Tue May 15, 2018 10:21 am
by hcanning
Thanks very much for your comprehensive reply.

That all makes sense.

The technician did state that he measured 100g of oil in the new compressor.

Is it likely that there is debris in the system if its the variable vane type of compressor with a failsafe shear on the pulley? Will it still chuck debris in the system?

I am hoping that when the technician returns, he will be able to find the leak without a working compressor to put the system under pressure?

I’m also hoping the leak (if there is one) is from the condenser or pipework and not the evaporator, since that won’t be a cheap job :(

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Tue May 15, 2018 1:55 pm
by JohnHere
The tech-verified 100 g of the correct oil in the new compressor should have been enough unless a lot of it leaked out someplace during the nine days you were operating the system. You could check for that yourself by looking for any oily spots on or near the A/C system's lines and components. Another possibility is that the replacement compressor was defective from the beginning, although if you installed a new original-equipment unit, I'd say that's a rather remote possibility. However, rebuilt compressors are not as trustworthy and are known to be less reliable compared to new units.
Even with a "fail-safe" drive pulley having shear pins on a clutch-less, variable-displacement compressor, it's hard to know whether either compressor, or both of them, shed any debris into the system unless you disassemble and inspect them. If you find that they disintegrated internally, then it's a pretty good bet that at least some debris found its way into the condenser. Regardless, I'd replace the condenser anyway to be sure you're starting with a nice clean, leak-free unit. I'm not sure about the 2007 Auris, but on some (many?) Toyota models, the receiver/dryer is integral with the condenser. So if you replace the condenser, you will also replace the R/D, which is good.
If the system still contains some refrigerant, the tech should be able to leak-check it without running it. If it's mid Spring where you are, the ambient temperature should be high enough to detect leaks since the ambient temperature roughly corresponds with the refrigerant's pressure with the system turned off.
Speaking of pressure, you didn't mention the low- and high-side pressures with the A/C system engaged and the engine running at about 1,800 RPM. System pressures could give us some additional clues about what's going on with your A/C. But maybe the shop didn't provide those to you.
You're correct about the evaporator being a major job time-wise. Usually, the dash has to be disassembled to gain access to it. Let's hope you don't have to go there.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Tue May 15, 2018 2:11 pm
by hcanning
Thanks again for your replies!

The compressor wasn’t OEM - well, it probably was once upon a time but I’m afraid I have to admit I went for the cheapest option of a refurbed unit!

I am thinking that I’ll spend a bit more on a new aftermarket one this time around - are even the cheaper ones usually a more reliable bet than refurbed units, then?

The condenser does indeed have the dryer built in, so that’s something. Are these the only places debris can collect?

I’ll check for any oily deposits and leaks around the condenser and hope there’s still some gas in the system!

Sadly I didn’t take note of the system pressures and have no way of measuring them, but the technician said they were about right.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Wed May 16, 2018 6:03 am
by JohnHere
The Auris is a European-spec vehicle that's not sold in the USA, where I am. So I'm not overly familiar with it. But a quick Internet search indicates that Denso was the OEM for your compressor. You could check with this site's sponsor to see whether they can source one of those for you or a comparable new unit made by others. Either would be preferable to a refurbished compressor, IMO.
Your condenser most likely is the parallel-flow type with very small internal passages, so any compressor debris won't make it past those micro-passages and will be retained in the condenser. Older tube-and-fin condensers have much bigger internal passages that could allow some debris to travel to the TXV and plug it. You shouldn't have to worry about the latter, though.
As for the pressures, we'll have to rely on what the tech said.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Wed May 16, 2018 6:08 am
by hcanning
Thank you!

So, am I right in assuming that the compressor, erm, compresses in the direction that the condenser is "first", so any debris pumped through the system by the compressor will only reach the condenser, and not flow to any other more remote parts of the system?

Thanks again.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Wed May 16, 2018 8:17 am
by JohnHere
Yes, you are correct.
A little theory: The compressor "compresses" the refrigerant, now in a gaseous state, from its internal chambers to the condenser and receiver/dryer, which are on the high-pressure side of the system. The condenser then changes the state of the refrigerant from a HP gas to a HP liquid, which then travels to the metering device (TXV). From there, the TXV changes the HP liquid refrigerant into a low-pressure liquid and meters it into the evaporator according to system demand. The evaporator changes the state of the LP liquid into a LP gas (and in the process provides cooling). The LP gas then returns to the compressor, and the cycle repeats.
It's very unlikely that any debris from a disintegrating compressor would make it past the micro-passages in a parallel-flow condenser and contaminate the remaining down-stream components. So I would expect that the HP line from the condenser to the TXV, the evaporator itself, and the LP line from the evaporator to the compressor's suction port would all be debris-free. Of course, there could still be a leak or leaks anywhere in the system.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Wed May 16, 2018 10:08 am
by hcanning

So I’ve had a bit of a look around with a UV light, and the only evidence of any leakage I can see is on the LP valve, here’s a photo:

Although this is probably just where it was filled?

The HP valve had no trace at all.

Re: Replaced compressor, failed again 9 days later. Advice sought

Posted: Wed May 16, 2018 7:14 pm
by JohnHere
I wouldn't worry about seepage at the Schrader valves as they're normally not bubble-tight anyway. It's the caps that do the actual sealing. Just ensure they're in good condition and snug them down well by hand. I like to put a little PAG oil on the internal o-rings, too.
So the leak(s) must be elsewhere. It's possible that the original compressor leaked at the shaft seal and/or a seam, and the same possibility exists for the refurbished compressor. Looking beyond the compressors would include the lines and hoses, o-ring joints, R/D, TXV, condenser, and evaporator.
You should probably leave further leak testing to your pro, who has the necessary equipment and knows what to look for. Leak testing is very tricky and can be very time consuming as well.