Contour Enthusiasts Group Archives Forums General Troubleshooting Air conditioning blows freezing cold one minute, hot the next....

I don't get it. Common sense would say it's low on R134 right? But sometimes the AC will blow freezing cold and then will become hot, then after 10 minutes or so blow cold again. If the R134 was low, wouldn't it blow warm all the time? Not in and out like that?

Their doesn't seem to be anything that sets it off. I turn it off, on, change the speed setting, turn the car off and on. It seems to be worse if i've been driving the car then stop it and restart shortly after. (10-15 mintues)

Has anyone ever heard of a problem like this before?

Evaporator coils freezing over?

Sounds just like what used to happen on my dad's IH Scout. Artic cold air + high humidity, then frost over, then hot air.

Your drain line could be clogged, too (my Scirocco had that nasty problem).

I just found something out yesterday. I was driving to Toronto and didn't have AC for about 45 mintues. Then all of a sudden on the highway I feel the compressor kick in and then cold air. It worked on the way home 5 hours later and then again today on a trip to Buffalo and back.

What would cause the compressor to just kick in like that after so long? I would says it's low on R134 but it's really cold when it kicks in which makes me think it's fully charged?

Bad compressor? I checked the drain line and condensation is coming out.

I had an odd experience this afternoon, too. I decided to celebrate the 80 degree temp by driving home with the A/C on. So I turned the switch, but no cold air. I drove for a few miles until I stopped at an intersection. When I started up again the A/C came on like always. I haven't been using the A/C this spring since I got the sunroof installed.
There was no noise like squealing or anything it just started up.

Think maybe the compressor is annoyed at the sunroof?

-Jim

Hey Jim,
Mine did the same thing...I tried to turn on the A/C while cruising on the freeway @ about 70 mph and nothing! As soon as I slowed to off-ramp speed the thing kicked on. It seems like there is a lock-out on the compressor to keep it from being actuated at high speeds...just a thought.

A/C at 80 degrees? Let's just say when the devil came down to georgia, he left hell here. a/c is reserved for 90 degree plus temps. i usually reserve mine for near 100 or over 100 temps. Though i think mine is not as cold as it should be,,,,, already have given it a shot of r134. accumalator maybe?

My guess is that it's not that cold because of the 100 degree + heat!

If you want to keep cool, get a Stratus. I was in my friends the other day and it was blowing so cold that my breath was freezing as I leaned over the vents.

Now thats cold!

if the AC system is not operaated regularly the refrigerant will "settle" into areas of the system and it may take a few minutes for it to start circulating.

A freezing evaporator coil is sometimes a sign of low charge, or maybe insufficent air flow.

intermittently going from hot to cold may be AC clutch problems, "sticky" pressure switches, or maybe something simple like a loose electrical connection on a pressure switch or the power wires to the compressor clutch..

J,

Pass me the bone you are smoking...

Have the system evacuated, replace the Orifice Tube, and add fresh lubricant to the system.
Then evacuate and recharge it.

You may have some moisture trapped in the AC drier, that once it gets into the system,
will freeze up the Orifice Tube, and cause a high pressure build up.
This triggers the High Pressure switch which shuts down the AC.
Since the comrpressor is a ONE WAY pump, the pressure will not relieve itself right away.
It takes quite some time for the high pressure to bleed down.
Once it does, the system has risen to ambient temperture and the AC Compressor
kicks in again to restart the whole cycle.

If the orifice tube is blocked up with metal shavings, your compressor may need to be replaced.
If it is blocked up with rubber, you may have a hose that is deteriorating on the inside.
If it is just iced up, then the AC was never evacuated correctly when it was assembled,
or last serviced.

NOT using your AC doesn't let refrigerant settle in different places.
The refrigerant is a gas and is throughout the system.
The synthetic lubricant will settle in the bottom of the tubes,
and the seals will not be thorougly lubricated, until the refrigerant
is pumped around, and it picks up the lubricant and spreads it throughout the system.
That is why you should run your DEFROSTER for the first 10 minutes you are in your car in the winter.
The Defroster uses the AC to dry the moisture from the air before it is heated and directed at your windshield.
If warm moist air was directed at your windshield, in the winter, it would
condensate immediately on the windshield, and block your view.

This is what I was always lead to believe, except that my service manual says that the A/C cycling switch prevents the compressor from operating below 50 deg F ambient temp to prevent evaporator freezing.