Engine AC freeze up

[Bruce H]

My engine AC seems to freeze up after using it for maybe an hour or so. I can hear what I think is the AC clutch chattering, When I turn off the AC the chatter noise goes away. I leave it off for a while and then turn it back on it will work for awhile. The hotter the temp outside the quicker it seems to freeze up. Gets pretty hot out here in Arizona. Any help on this subject will be appreciated. Thanks Bruce H

[Bruce H]

My engine AC seems to freeze up after using it for maybe an hour or so. I can hear what I think is the AC clutch chattering, When I turn off the AC the chatter noise goes away. I leave it off for a while and then turn it back on it will work for awhile. The hotter the temp outside the quicker it seems to freeze up. Gets pretty hot out here in Arizona. Any help on this subject will be appreciated. Thanks Bruce H

[CSX4350]

Bruce, it sounds like you're either low on freon or over filled.

[Hillbilly2]

Also check and make sure the condensor is not clogged with bugs, it looks like a smaller radiator, and usually sits in front of the radiator. Be carefull not to bend the fins cleaning it though, they are very fragile and will flatten out easy blocking air flow.

[Poltax]

First thought low freon. Nex thing would be the condensor clutch.

[D in Davie]

Out in Arizona there should be some good AC mechanics who can find the leak for you. Don't let it go too long as it will overheat the compressor and cause further damage. You should inspect all connections and joints on the lines running from and to all of the components that you can see. If you see things that look wet or oily or red then that is where the leak is. Joints leak the most, the long ones the most because they vibrate. If you go in armed with the knowledge of where the leak is you can better figure out if you are dealing with an honest mechanic. JMO

[rclarke]

All these things can cause your problems but check the simple things first. A loose belt can make a clattering noise and may need replacing or just tightening.

[sparetire]

I don't know your setup...DP, gas, side radiator, etc.) The very first thing to look at and make sure it is running the moment you kick on the A/C is the condenser fan. Even engine driven cooling fan systems will still have an electric puller or a pusher condenser fan. What you call chatter is most likely high compressor head pressure slapping the reed valves shut. It is an indicator of too much pressure and can cause the compressor to fail quickly.

On the other hand:

Most A/C systems have a thermostat unit in the evaporator which will kick the compressor off at 30 degrees. If it is truly freezing up, then the head pressure is too low for the refrigerant gas to carry the compressor oil and you are then hearing oil starvation and piston scuffing. Either high or low pressure conditions are bad. If you don't know an evaporator from a condensor, take it to a pro automotive shop like Arizona Mobile Air. I have ordered parts from them and they are great to work with from that perspective. I don't live in AZ and have never been in their shop but I'd take my Safari to them if it broke on the road in the summer in AZ!

Happy travels,
Sparetire

[Bruce H]

I appreciate all the great advice from all of you. You have armed me with enough information that when I take it to a repair shop I will be at least somewhat knowledgeable. I will check out some of your suggestions that I can do myself. When I do find the problem I will post the correction with the hope it helps someone else. Thanks again, Bruce

[Bruce H]

Update on the AC freeze up. Turns out it was low on freon as some of you suggested. I took it to an authorized Work Horse service center. They found it to be low on freon and evacuated the system removing 24 oz. of freon and reinstalled plus 16 oz.. I asked if it was low there must be a leak. They said they could not see any visible signs of a leak and when they evacuate the system sometimes that takes care of it!! What are your thoughts on this? The MH is nearly 5 years old with 26,000 miles.
Bruce H

[M&EM]

Mine needed freon last year about 1 1/2 cans (about 18 oz) after almost 5 years. Probably very slow leak?
Re vacuuming is best way to get right amount back into the system and remove unwanted gases (like air)