Automotive Air Conditioning Information Forum

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am I use a product called Pittstop to estimate the quantity of oil in the AC system.

I've never used Pittstop and have concerns about its accuracy. Others might disagree, but I feel much more comfortable doing it the old-fashioned way, starting with a completely empty system, then physically adding the exact amount and type of oil the specs call for.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am On my Civic, before the compressor replacement, Pittstop was showing a very low quantity of oil in the system, which I thought it was possible, because refrigerant had been added to the AC system in a couple of occasions (because of leaks) without adding oil.

I think that if the oil amount was a low as Pittstop indicated, the original compressor would have disintegrated internally and/or seized up...something you definitely would have noticed. If the leaks were small, it's possible that oil loss was negligible.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am When the compressor was replaced, the new compressor came with 3 fluid ounces of oil and we did not add any other oil, because the shop estimated that there were other 2 fluid ounces distributed in the AC system.

That probably was a valid estimation. But whatever old oil was still in there might have been contaminated with moisture from past servicing, or it might have simply worn out. We don't know for sure. So instead of risking damage to the new compressor, I would have flushed everything that could be flushed, cleaned out the old oil, and added fresh oil. I also would have drained the oil out of the new compressor and refilled it to ensure that 3 ounces were actually inside.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am The quantity of refrigerant (should be 18 ounces net weight, as you stated) that was put in the system was not weighed, but was estimated by the shop, based on the pressures. Unfortunately I don’t have those pressures.

Recharging by weight is the only reliable method to ensure the refrigerant charge is precisely correct. Because the Civic holds such a small amount of R-134a, a charge that's just a half-ounce off can and will affect cooling performance. So at this point, it might be under-charged or over-charged--we just don't know--since the shop charged it only by pressures, which tell us nothing about the actual *amount* of refrigerant contained in the system.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am I don’t have the old TXV any more. The TXV and the evaporator were replaced by another shop last year. They claimed that they used a quality aftermarket TXV (OEM equivalent).

If the system doesn't work right after everything else is corrected, you might be able to get an OEM TXV from Honda, which IMHO will be superior to and more costly than an aftermarket replacement.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am To summarize the current AC system situation is the following:
• As stated, Pittstop reads very low quantity of oil
• AC works reasonably with outside temperatures in the low eighties, but poorly with temperatures around 90°F. The temperature of the air coming out of the vents is 68°F, measured with a food thermometer
• There is a noise coming from the AC system. It is not a grinding noise. It is more like a howling noise, not loud

A 68-degree vent temp isn't going to be very comfortable on a hot day, as you already know. I believe that particular system should cool down into the 40's if it's working right and has the correct charge. I'm not sure about the noise. Is it coming from the dash or under the hood? It could be the blower motor or the TXV, which can make noise if it's not the right one or if the charge is off.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am Is it possible to flush the AC system effectively (excluding metal debris, of course) by removing the compressor and connecting to the lines where the compressor was, without removing other individual components?

My concern with that method is getting out all traces of the flushing solvent. Sometimes, depending on how it's installed, you can flush the evaporator in place. But I think it's best to flush the other components separately and removed from the vehicle.

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am What would be a good AC gauges/vacuum pump kit for me to buy for personal use (CPS, Yellow Jacket) ?

Check with Tim at ACKits.com, the site sponsor, who can set you up with whatever you need.

JohnHere,

Many thanks for such detailed answers to my many questions.

Unfortunately it is too late to take action on most issues, since in my Civic there is no easy access to many of the AC components, including the compressor.
But I'll make sure that the pressures are in spec and that there are no leaks. And, if something goes wrong with the AC in the future, I know what was done incorrectly in the past and I have an understanding of how to proceed.

Charles5654 wrote: ↑Tue Jun 08, 2021 9:17 pm JohnHere,

Many thanks for such detailed answers to my many questions.

Unfortunately it is too late to take action on most issues, since in my Civic there is no easy access to many of the AC components, including the compressor.
But I'll make sure that the pressures are in spec and that there are no leaks. And, if something goes wrong with the AC in the future, I know what was done incorrectly in the past and I have an understanding of how to proceed.

Our pleasure. Come back and see us anytime.

Al9 wrote: ↑Wed Jun 09, 2021 1:59 am

Charles5654 wrote: ↑Tue Jun 08, 2021 10:05 am Is it possible to flush the AC system effectively (excluding metal debris, of course) by removing the compressor and connecting to the lines where the compressor was, without removing other individual components?

No. The drier has to be removed and bypassed (it's a filter), and the TXV will close once a certain evaporator pressure (the MOP) is exceeded, preventing the flush agent from flowing around (unless its metering pin has been removed). I had to supply a second hand Denso 447500-1600 TXV and remove the spring and the metering pin from inside (undo the bolt, and they come out) when they flushed my car's AC. I'm sure they used it because it had some black crud when they gave it back to me. The shop lacked the proper flush adaptor that replaced the old TXV.

Thank you for your clarifications.