110°F here today in sacramento. so, i'm really testing out the A/C circuit.

the past two days the A/C has cut out on me at the same spot on my drive home--about 20 minutes into the trip. when i say 'cut out' i mean the air coming out of the vents is no longer chilled. it's acting like the old days when the evaporator would freeze and i'd have to cut off the A/C for a few minutes to let it melt. i've just never had any trouble with this truck/a newer computerized car before.

so, is this normal (remember it's 110° outside), or is something wrong? i'd always thought there was a relay on the compressor fed by the computer that would cycle the clutch to keep the evap from freezing.

anyway, before i take this in for service, i thought i'd get some opinions. can't live without the A/C in this weather for very long.

thanks.

 

same place,

Was it a steep incline or something else that puts extra strain on the engine? Thats a case of vacuum leak. Search Vac leak, Check valve, and A/C and you'll find lots of info here.

 

It's either a high or low pressure problem. Given the 110 ambient temp., I would suspect high pressure is cutting the system off...as it should. But, why is another question. It is not normal. While it may not blow at 40 degrees in 110 outside temp., it should not cut out. Without a manifold ga. set reading, impossible to tell exactly. Are the condenser fins clean? Is the fan/clutch in proper working order? Could be blockage internally.
WC

 

no special strain or incline. actually, that part of my drive is a pretty flat 45mph in cruise control...coming up to a traffic light where i stopped and fiddled with the swtiches for a minute (to no avail). then, back up to 45mph for another 1.5 miles and, fiddled with the switches again at the next light. back up to 40mph and the A/C kicked back in (just like yesterday) for the remainder of the 10 minute drive home.

Wayne, i'm a little puzzled by your statements: first you say "suspect high pressure is cutting the system off...as it should." But, then you follow that by "It is not normal". can you elaborate on what is supposed to happen?

i guess tomorrow i take the IR thermometer with me. i can't really tell you what temp it is blowing when it cuts. for sure it's not the normal 40°...but, i suppose it could be still putting out *some* cool air. but, i definitely started sweating between the traffic lights. 110° takes it toll on a little greenhouse pretty quickly.

thanks for all the tips. i'll check the condenser and clutch this evening after the outside temps drop a bit.

 

It is not normal for the system to drop out like that. However, as a safety mechanism, it the pressure gets too high (which under "normal" circumstances should not happen) the compressor will shut down. If that fails there is also a high pressure valve on the compressor that will blow and relieve the pressure. Hope that helps.
WC