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View Full Version : need advice on the proper way to install an a/c expansion valve



POS carb
07-10-2012, 12:32 PM
I'm going to redo the accord a/c,
need to know what is the correct way to mount the coil that comes off the top of the expansion valve for proper operation (should I stretch it out, avoid kinks, leave it alone, etc. what's the best place to mount the tip)

looks similar to this:
http://www.jeepair.com/images/products/medium/204flvalve.jpg

Also, should it be mounted near the inlet or the outlet of the evaporator?

DBMaster
07-10-2012, 03:07 PM
Have you yanked the old one? What did it look like? I am in the residential A/C industry and one of the commodities I buy is expansion valves. As far as I know the coiled part should be left the way it is and you just need to get it up against the evaporator - out flow side. It is a capillary tube that, based upon the output temperature, determines how much liquid refrigerant is allowed to expand into gas in the evaporator. When they malfunction you end up with frozen coils.

86dxhatch
07-10-2012, 03:35 PM
So Mike, it doesn't get attached to the suction line like a residential system?

DBMaster
07-10-2012, 03:41 PM
The capillary tube does not. The expansion valve on a residential system is typically installed on the high (liquid) line just before the evaporator coil. The suction (low) side is the larger line that gets cold and returns the low pressure gas back to the compressor to be turned back into a liquid. Think of the expansion valve (TEV in manufacturer-speak, TXV when my company refers to it) as a metering device for the liquid refrigerant.

nswst8
07-10-2012, 05:51 PM
It's goes to the longer thick pipe (use dum dum insulation tape) , not the one coming up from the bottom where the TXV bottom connection goes.

88Accord-DX
07-10-2012, 06:01 PM
That whole set up is near the evaporator core. The capilary tube goes on the bottom of the evap core & near the center on the end of it... Be careful with the copper tubing placing it on the evap core & have a clip to hold it to the fins..Pull a good vacuum on the system for 10 minutes before charge...

DBMaster
07-11-2012, 12:09 PM
This is an article about residential TXV's, but it should apply to your situation as well.

http://www.achrnews.com/articles/quick-facts-txv-selection-and-sensing-bulb-location

The coiled tubing on the one in your photo acts as the sensing bulb.

POS carb
07-11-2012, 01:55 PM
This is an article about residential TXV's, but it should apply to your situation as well.

http://www.achrnews.com/articles/quick-facts-txv-selection-and-sensing-bulb-location

The coiled tubing on the one is your photo acts as the sensing bulb.

great info, perfect! Thanks!

Dr_Snooz
07-11-2012, 10:14 PM
When I replaced mine, I just peeled back all the black glop Honda had put all over it and ran it the same way it was run before.

Hey, it worked for 20 years that way.

Uh, well, most of those 20 years. When it worked. It is a Honda A/C after all.

I think the only real issue was getting all the screws and clips out of the evaporator case. Getting it back together also is more of a jab and mash job than anything resembling perfection. Take the opportunity to give it all a thorough cleaning. You won't be going back in there for a very long time again.