Weird AC issue on my Civic

[Formula413]

I had an issue with the air conditioner on my Civic when I went on my trip, trying to figure out what the deal is. Four days into my trip the AC became intermittent and then stopped working altogether (not fun when you're driving through the southwest). But I figured out that it would work when the engine was not under load, IE idling or coasting.

Stopped at a garage in Texas to have it looked at, the guy said the low side pressure was low but when he tried to add refrigerant it all went to the high side, and he thought the compressor might be going out.

Next day I had a Honda dealer in Albuquerque look at it, they said the system was actually overcharged (obviously from the last guy trying to add refrigerant) and they said that they thought the problem was that the AC was set to economy mode. Never mind that is has always been set to economy mode ever since I've owned the car and always worked fine. They evacuated and recharged the system and pronounced it good, which it was for about 15 minutes. So much for the dealer having all the answers.

Skip ahead a few weeks, I'm in the midwest in the middle of an oppressive heat wave. One day in Iowa I try turning on the AC just to see what happens, and sure enough it's working, load or no load, and has been working fine since.

The only variable I can see between when it worked and when it didn't is the elevation. Western Oklahoma and the Texas panhandle, which is where it started having problems, is also where the elevation starts to increase heading towards the continental divide. From there much of the trip was at elevations of 4,000ft-7,000ft or more, except along the west coast where it was cooler and I didn't try to use the AC. And eastern Nebraska and Iowa is where it dropped back down to about the 1,000ft range. Could elevation have anything to do with the AC not working? Or is it just a coincidence?

[ILuvPizzaTimes10]

Orfice tube or reciever dryer are plugged. Causing a high side pressure and the low side to drop off. The refirgerant isn't circulating well. Have it vacced and change both if your system has them. And look for small aluminum filings. If there are any the compressor might be going as well. Causing the blocked filters.

[84ta406]

Agreed with pizza, we had a similar problem on a motorhome here

[Formula413]

I thought that a plugged orifice tube or expansion valve would make sense, I just don't know why it started working again, unless whatever was plugging it moved. I can see the dryer but I'm not sure where the expansion valve/orifice tube is, the lines go into the firewall so unfortunately it's probably behind the dash.

[98 hoe]

usually they r in the line look for crimp marks right after a connection in the ac line thats where the orifice tube is. i agree with pizza as well. do u know if that uses vaccum solienoids or electric ones to opperate the hvac temp doors?

[Formula413]

I looked up parts for it and it uses an expansion valve. It's hard to tell from the diagram but if it's not in the engine bay it must be behind the firewall.

As for the blend door control I'm not sure. Had all that stuff out to install the stereo but I don't remember what was back there. It's climate control is that tells you anything.

[ILuvPizzaTimes10]

they would be electronic with climate control. and Not ALL cars have an orfice tube and use piping diameter to get the pressure difference. look it up online for Your specific car. and yes the blockage could have moved. elevation has little effect on A/C so leave that out.

[Formula413]

I thought cars had either an orifice tube or an expansion valve but not both, is that not correct? Looking at a parts list on a Honda parts website I didn't see an orifice tube listed.

[98 hoe]

Yes it will either have an oriface tube or an expansion valve.

[ILuvPizzaTimes10]

not always the case. the ford escort say mid 90's(only one i can think of off the top of my head) ran both. certain small cars with not alot of power ran both for better pressure differance to help aid in power loss under load.