Hi guys. I have a 2003 honda civic with 97000 miles and the air conditioner starts up fine. Then anywhere from 5 minutes to 30 minutes later the ac cold air just fades out and it briefly blows moist lukewarm air that turns to ambient air temp. The cold air seems to fade out after I slow down from highway speed and the load on the engine lessens. Possibly related, is another problem which is when I accelerate hard to say join traffic on the highway the cold air fades out and then as the engine levels off the cold air comes back. The blower motor works fine. Any thoughts?

When you first start it up, is it cold even when sitting idling?
Will it come back on if you shut the A/C off for 30 minutes?
.
.
.
.
.
.
.
.




78 Corvette Pace Car For Sale-18k mi orig-Florida




(This post was edited by Hammer Time on Jun 17, 2009, 12:30 PM)

Thanks for the fast reply Hammer. Most times when I start it, it will blow cold but not allways. Kind of a fickle thing. Yes after about 30 mins it will work for a shorter period of time.

Sounds like the evaporator core might be freezing up and thawing back out. That would mean it has a bad thermostat at the evap but you need to see if the return line is cold when this is happening.
.
.
.
.
.
.
.
.




78 Corvette Pace Car For Sale-18k mi orig-Florida




(This post was edited by Hammer Time on Jun 17, 2009, 2:13 PM)

The core could be freezing up as suggested. Also Honda's are good for their expansion valves sticking. To diag that you would need a manifold gauge set & check your pressures. At higher rpms, if the low side drops into a vacuum, you have a sticking valve.....

Quote

That's very true but if he feels the temp of the suction line as I suggested, he should be able to tell right away if that is the case or not.




78 Corvette Pace Car For Sale-18k mi orig-Florida

Definately....Touch test is quick, easy & points you in the right direction.....

Ok how do I find the correct line to test?

This has to be done during the period when you have lost cooling.
Feel the line coming out of the firewall and going to the compressor (large line). If it's ice cold, then the gas system is fine and your problem is freeze up.
If it's not cold, feel the other line going from the firewall to the condenser. It should be warm to the touch. If it is only room temp, then you have no circulation and a likely bad expansion valve.
.
.
.
.
.
.
.




78 Corvette Pace Car For Sale-18k mi orig-Florida