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Need help from the pros on this one.

Metal Man on Thu November 08, 2012 8:28 PM User is offline

Year: 2001
Make: Honda
Model: CR-V
Refrigerant Type: 134a
Ambient Temp: 60
Pressure Low: -30
Pressure High: 70
Country of Origin: United States

OK guys, customer brigs in a 2001 Honda CR-V and tells me he has a leak in the AC system and points at the low side schrader valve. Says he seen it bubbling around the needle. I ask how long he has had the vehicle and he says one day(which is evident by the car sale number still on the window) vehicle obviously has a brand new compressor and dryer.

So i replaced the schrader valve,vacuumed the system down then recharged to the proper amount. First red flag was when my machine had a hard time added the 134a. The system held what it called for but it took longer then normal to charge. Once i started the car up with AC on max i seen there was a problem. The low side went into a vacuum and bottomed the gauge out at -30. The high side stayed still at 70psi (static pressure). I realized there was a blockage but was a little unsure were it was at.

This is a thermal expansion system. The low side port is located about 12 inches from the compressor. The high side port is located between the condenser and dryer.

This is were i get confused. I figured since the high side pressure stayed at 70psi and the low side went into a vacuum that the condenser must be blocked. When i start taking the radiator out to gain access to the condenser i notice the condenser is brand new. That means this car has a new compressor,dryer and condenser. Someone has obviously already been trying to fix this problem.Thats when i start thinking it might be the thermal expansion valve.

But would the TXV cause the low side to go to vacuum but the high side remain at static pressure????? thats were i get lost.

What do you guys think?

mk378 on Thu November 08, 2012 10:20 PM User is offline

Likely the TXV. The backstory suggests a strong possibilty that stop-leak has been used.

High side stays low with a total blockage because with no refrigerant flowing there is no heat transfer, thus the refrigerant all condenses at ambient temperature and sits as liquid in the condenser.

doctorbee on Thu November 08, 2012 10:39 PM User is offline

oh boy, i hope the customer got the car for cheap. this sounds expensive. i hope there isn't any QUEST STOP LEAK in the system.

Dougflas on Fri November 09, 2012 5:10 AM User is offline

Pull the TXV bulb loose. Place it in an ice water bath and then hold it in your hand. You should see a pressure difference. If not, most likely a bad TXV.

NickD on Fri November 09, 2012 7:19 AM User is offline

Not only stop leak, PAG does that if exposed to any kind of moisture. An experiment was done years ago mixing PAG with water in a Mason jar, even after a month of drawing a deep vacuum, PAG remained as a paste.

Never had this problem with R-12 and mineral oil, instead of making life easier, made it a lot more miserable, we are just going backwards. But a lot more work, (and money) for the tech.

Metal Man on Fri November 09, 2012 7:28 AM User is offline

Thanks guys. I'll break the bad news to him in the morning.

Edited: Fri November 09, 2012 at 7:29 AM by Metal Man

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