Did an inspection last week and the exterior AC compressor was labeled R-410 coolant, but the cooling system in the attic was labeled R-22. We call this out. Although we only are required to test and report on the functionality of the unit was this the right thing to do?
Yes, simply check the system for functionality. If you have HVAC knowledge, training etc. all the better to help you inspect. However, its best to stay within the scope and SOP of home inspecting.
The coil was likely old stock and the system would be charged with R410A.
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Scott, thanks for the reply. So was it the right thing to do or was it exceeding the standards in your view as a Master Inspector and we should not do point it out going forward should we see it again. We have no formal HVAC training, but we have done our research on what will happen with two incompatible systems and thought is waise to point it out to or client.
Ok for conversation but would most likely just create confusion.
When you recommend in your report, have a licensed HVAC company conduct a clean and check service, this would hopefully be noted.
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Did this very thing with my own system a few years ago - R410A condenser and slightly older R22 coil. We simply adjust the amount (added) R410A to compensate.
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Label under my hood reads 410a but the system has 12a. I know that because I put block-offs for the rear unit, vacuumed and installed 12a. 410a is not available off the shelves in Canada but 12a is and is compatible with the system.
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Don, I know that Scott knows his HVAC stuff…No offense, Marcel, and it sounds like you know what you are talking about, too. 
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Report your observations.
Recommend referring to the manufacturer’s to see if that piece of equipment, model# evaporator can updated/converted to R401A refrigerant.
Converting HVAC Equipment from R22 to R410A refrigerant can be achieved in most cases. Line pressure is reduced.
Just my 2 cents.
I have been doing inspections since 2007and thus year was the first time I ran into this. My cooling guy stated that in the early days of the refrigerant change, if the test pressure of the coil was>300 PSI, they would change out the metering device , evacuate the system and charge with the newer refrigerant. This sounds like what you ran into? Frankly, until then, I NEVER even thought to check for evaporator and condenser comparability.
Reviving this thread. I have an opposite situation, the exterior condensing units are rated for R-22 and dated the year of 1998. The interior evaporators have been upgraded to 410-A and dated 2012.
It was too cool to operate the AC system so I did not check for functionality.
If they reused the exterior housings and replaced the guts like compressor, capacitor, etc., would that be acceptable or a defect to refer out to a licensed HVAC company? Seems to me that using the old exterior condensing units wouldn’t be the best idea, especially for a 6 million dollar home.
Edit: Should I just stick with this narrative that I found on a similar post (edited for my situation)?
“Condensing unit (R-22) and evaporator coil (R-410A) are labeled for different refrigerant types and may not be compatible with each other. Recommend verification with the manufacturer or qualified HVAC contractor whether these two units are compatible and replace components as necessary.”
Had the interior unit replaced in the 90s (evaporator). Had a tiny leak somewhere and had been refilling it every year (R12). New system still uses the same condenser. Refrigerant has to be 410 or better. Nary a problem.
My practice is to report on functionality ONLY.
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Our practice is to also report on functionality only since my original Sept 2020 post.
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If these have been installed for any length of time, I would simply make a note of it in the body of my report to have it verified during their next scheduled servicing and include a limitation that you could not test it due to outdoor air temp. I would also have the conversation with the buyer.
R410a runs at a higher pressure so if it ever worked, it was made compatible.
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No.
First, this is not your job. You are allowed to go outside the SOP if you are qualified. You stated you were not, so no.
The only time there is an issue (if the installation was done by a competent installer) is that some cheap evaporator coils were used with R-410a which has higher refrigerant pressures. All others simply require the metering device to be changed for the correct refrigerant, or adjust the TXV properly. This is only if the unit is a Heat Pump. You called this a “cooling system” not a Heat Pump, so this HP stuff does not apply to your case.
If either indoor or outdoor component is replaced, you will find this mismatch. At a point in time when R-22 was stopped (for no reason except for expiring patents) new equipment was sold with in stock R-22 coils.
When the HVAC guy replaces a component, the replacement is matched at the parts supplier. Often, the Mfg is contacted concerning compatibility before it is sold.
You couldn’t turn it on, so you only have that to point out.
If you didn’t run the unit, for whatever reason, why would you feel compelled to discuss anything about this? Who is going to pay for that HVAC Guy to come look at those stickers? He can’t check the metering device in that A/C without a $1k job to check the installed metering device.
You pointed out that you’re “Not required”, as well as you’re “Not formerly trained”. The SOP says you can exceed the SOP “If you’re qualified to do so”, so that answers: