AC manifold guages, cross contamination really a worry?

[cb474]

I replaced the ac compressor in my Mazda 3 and now need to recharge the system. I was going to take it into an ac shop to have it charged, but they're not available until Monday, so now I'm thinking of borrowing the vacuum pump and manifold gauge set from O'Reilly's and just doing it myself, for less money.

However, I read some comments about how you shouldn't use the same manifold gauge set with different refrigerants and oils or you risk contaminating your system. Of course, I have no idea what has been done with a set of gauges borrowed from the parts store. Should I really be worried about cross contamination or are the amounts left behind in the tubes such trace amounts that it doesn't matter?

I guess I could also buy a cheap set of gauges from Harbor Freight, but then I wouldn't be saving any money on the recharge.

 

[Chris142]

Any refrigerant will boil off immediately. A little drop of different oil won't matter. My ac machine shoots in whatever oil I put in it. I'm not worried about it.

 

[nthach]

Don’t use that gauge set on a hybrid/electric car. The newest HVAC RRR machines don’t do oil injection anymore - and dealers keep a separate machine to service xEVs.

PAG contamination in xEVs is real - and will set a code for voltage leak to ground, which also means a no-crank/no-go. For the most part, PAG oils used in automotive HVAC are miscible with POE oils that were used for retrofitting R-12 automotive systems to R-134a, and are used in electric AC compressors. Else, POE is used in stationary HVAC/R.

 

[Chris142]

Don’t use that gauge set on a hybrid/electric car. The newest HVAC RRR machines don’t do oil injection anymore - and dealers keep a separate machine to service xEVs.

PAG contamination is real - and will set a code for voltage leak to ground, which also means a no-crank/no-go. For the most part, PAG oils used in automotive HVAC are miscible with POE oils that were used for retrofitting R-12 automotive systems to R-134a, and are used in electric AC compressors. Else, POE is used in stationary HVAC/R.

True but is his Mazda a hybrid?

 

[nthach]

True but is his Mazda a hybrid?

Nope - but you never know if he’s gonna help out a friend with one and plans on a well-intentioned pressure check.

 

[cb474]

True but is his Mazda a hybrid?

I wish Mazda offered more interesting versions of the Mazda 3. The fuel economy is the one thing that's really disappointing on this car. In Europe they have diesels and the SkyActiv X, but in the U.S. the options are so limited.

Nope - but you never know if he’s gonna help out a friend with one and plans on a well-intentioned pressure check.

My partner does have a Prius, so I appreciate the heads up. Although I think the Gen 1 Prius just has a regular old ac system like most cars. Things got different with the Gen 2 Prius, if I'm not mistaken.

 

[nthach]

My partner does have a Prius, so I appreciate the heads up. Although I think the Gen 1 Prius just has a regular old ac system like most cars. Things got different with the Gen 2 Prius, if I'm not mistaken.

First gen Prius as well as the first gen Honda Insight/Civic Hybrid use a regular engine-driven compressor. Honda commissioned from Sanden or Keihin a convoluted dual-mode compressor on the 2nd gen Civic Hybrid and Accord Hybrid.

 

[cb474]

Somewhat tangentially related to this question: When I installed my new compressor, drier, and discharge/high pressure line, I added 3 oz of oil to the compressor and 1.5 oz to the discharge line. When I pull a vacuum on the system, before charging it, how is the vacuum pump not going to suck some of the oil out of the discharge line (since the manifold gauges connect directly to that line)?

I have not run the compressor yet, to circulate the oil through the system, since I figured that would not be good to do with no refrigerant in the system (and I assume it wouldn't engage anyway, because the low pressure switch would prevent that).

 

[Chris142]

. When I pull a vacuum on the system, before charging it, how is the vacuum pump not going to suck some of the oil out of the discharge line (since the manifold gauges connect directly to that line)?

In order to suck the oil out the vacuum would need to have an open end like a straw. Since it's a sealed system it wont pull any oil out

 

[Fitter30]

What refrigerant?