06 Civic-Insufficient Cooling

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PromiseRing
Posts: 33
Joined: Thu May 24, 2018 2:28 pm

06 Civic-Insufficient Cooling

Postby PromiseRing » Fri Jul 26, 2019 12:59 pm

A friend of mine just bought an 06 Civic 4 door from a Buy-Here-Pay-Here lot and the AC is not cooling as it should. Lowest vent temps we can get are 58-62F and it just never cools down.

Evacuated, vacuumed, and recharged the system by weight and here are my results.
Ambient temp: 83F
Vent temp: 60F (at idle)
Low side: 34 psi
High side: 200 psi
Both cooling fans on, moving lots of air over the condenser.

When engine was revved to roughly 1,700-2,000 rpm,
Low side: 19 psi
High side: 275 psi

Vehicle was said to have a new compressor. I was thinking maybe the compressor failed and partially clogged the TXV? I am lost on this one. Any help appreciated.

Oh, and I don't think it's a heater control valve issue, because the problem remains the same on a cold engine before the coolant has a chance to warm up.
K6ORJ
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Joined: Sat Jul 27, 2019 5:08 am

Re: 06 Civic-Insufficient Cooling

Postby K6ORJ » Sat Jul 27, 2019 5:30 am

At 275 psi your head pressure seems a bit high for an 83° F day. TXV's usually fail shut, so after the system is shut down it should come close to balance through the metering device (TXV) within 15 minutes or less. If it takes long time like 30 minutes or more, you most likely have a bad TXV. Be careful not to over pressurize your blue gauge when doing this test, it shouldn't go into RETARD! Also cooling should get worse as the ambient temperature rises, because the TXV isn't opening up to set the superheat.

The filter-drier should protect the TXV from getting clogged with trash if it is intact.

Did the filter-drier and the condenser get replaced with the new compressor? Your high head pressure leads me to check. The filter-drier and condenser. If the compressor pushed trash through the system it might have a bad condenser. That would give insufficient to no subcooling. Meaning the refrigerant would not have fully condensed into a liquid. Insufficient subcooling is bad, the system must feed the TXV liquid refrigerant with no bubbles.

After a restrictions in the high side can cause the refrigerant be slightly cooler right after the restriction. This is because the liquid is flashing back into a gas. When this happens it absorbs heat. You don't want the refrigerant to absorb any heat on the high side of the system.

If the condenser is bad the only option there is to replace it and the filter-drier there's no way to flush out of the tiny holes in the condenser.

Air in the system can also cause a high head temperature because it can't pass through the liquid line. It gets trapped in the condenser like air in a cave. This air doesn't allow the refrigerant to contact the walls of the condenser coil preventing cooling.

If there's dirt on the outside of the condenser it will not be able to cool the refrigerant Make sure the outside of the condenser is clean, careful not to bend the fins.
PromiseRing
Posts: 33
Joined: Thu May 24, 2018 2:28 pm

Re: 06 Civic-Insufficient Cooling

Postby PromiseRing » Mon Jul 29, 2019 8:50 am

Thank you for the reply. Unfortunately, I have no back story on this car other than that 'it has a new compressor', which we’re not even sure if that is true. However, condenser appears original so I doubt it was replaced. Also since it was a used car lot, I'm highly doubting they replaced anything other than the compressor.


That 275psi head pressure was at an elevated rpm but at idle. It’s on the upper end of the spectrum, but I think I may have slightly overcharged the system which could be causing that number. I understand that it needs to be charged again by weight, but I do not believe this to be the main cause of my issue.

Has anyone ever seen a clogged filter dryer inside the condenser actually cause insufficient cooling like this? If so, I’m wondering if I can get away with just replacing that filter dryer. I’d like to think that filter trapped all the contaminants and he condenser is okay, but of course that is just wishful thinking. In a perfect world the condenser will be replaced too but we need to see how much the car lot is willing to work with us.

I am just curious if there’s a way to determine whether or not we have an issue with the condenser and/or filter dryer rather than the TXV. I could do a current draw test on the compressor. If it’s not drawing much current and changing the load on the engine (like it should) would that indicate that the compressor is not receiving refrigerant properly after it travels through the evaporator core? This would say to me that there’s a restriction somewhere in the system.

I can let the AC run and then shut it off and wait to see how long it takes for the pressures to equalize. You said 15 minutes maximum is a good baseline number?

And there shouldn’t be any air in the system. I vacuumed it for a while and it was in a very deep vacuum.
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bohica2xo
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Re: 06 Civic-Insufficient Cooling

Postby bohica2xo » Mon Jul 29, 2019 9:35 am

The condenser is the primary filter on the system. When a compressor fails & sheds pieces, they go straight to the condenser.

Parallel flow condensers have tiny passages - in parallel. When the trash blocks one passage, you lose cooling capacity. They are hard to block completely, and are nearly impossible to reverse flush because of the parallel passages. Replace the condenser.

.
PromiseRing
Posts: 33
Joined: Thu May 24, 2018 2:28 pm

Re: 06 Civic-Insufficient Cooling

Postby PromiseRing » Tue Jul 30, 2019 7:06 am

bohica2xo wrote:The condenser is the primary filter on the system. When a compressor fails & sheds pieces, they go straight to the condenser.

Parallel flow condensers have tiny passages - in parallel. When the trash blocks one passage, you lose cooling capacity. They are hard to block completely, and are nearly impossible to reverse flush because of the parallel passages. Replace the condenser.

So I need not worry about a TXV issue right now?

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