Truck Airconditioner


I have a 2001 Dodge Diesel 3500 1 ton 4 wheel drive, I' towing a 38 ft travel trailer, I doubt if anyone can answer my question but I thought I would give it a shot.

About a year ago my airconditioner went out and the repairman discovered it was the heater core that was leaking so he replaced it and put everthing back togeather and I had really cold air, however the cold air was only coming out at the floor vents, so my repairman took the dash off and found a plastic control connection for the controls had broke so he replaced it and it was about and 80 cent part but took 8 hours to take apart and put back togeather.

Well every thing worked for awhile but then went back to blowing cold air just out the bottom floor vents, so we are now on the road and when we turn on the air we have to move the control knob back and fourth from maxium air to the top vent air to get cold air to come out at all, it is a hit miss situation.and after awhile we can get cold air coming out but it is still at the bottom vent.

So this morning I'm driving from the Reo Grande to Corpus Christi and it quits blowing cold air again so I do all my little control movememnts back and fourth to try and get it going but with no luck.

So when I pull into the camp ground and get all set up I took a look at the airconditioner, it didn't sound like the compressor was kicking in and out when I switched the controls, so I'm figuring that now the compressor has gone south on me and as it runs the airconditioner lines are not frosting up, so I piddle with things for awhile and I check the fuse and find I have a 10 amp a/c clutch fuse is blown, so I figure that is my trouble I replaced the 10 amp fuse and I thought I had found the trouble and when I turned on the air it sounds like the aircompressor is kicking in and as I held my hand down at the floor vent it seemed like it was starting to cool off and when I put my hand on the aircondion lines running from the compressor it felt as if it was trying to cool but then it seemed to quit cooling so I check the fuse again and it has blown again.

So I'm out of 10 amp fuses so I put in a 20 amp and it blows it again, so now I'm wondering if anyone has any ideas is the control switch on the dash bad and causing a short or is my compressor going bad or what is going on? any ideas out there, and if I have a diagosis check done will that tell me what is wrong? or will it tell me if the compressor is bad? I don't have a clue.
I thought at first maybe with me turning the airconditioner control off and on to get it to work may have cause the fuse to blow initialy, but after I changed the fuse I put the control on high cool and then I started the truck with out switching it and it still blew. If anyone out there that has knowledge of airconditioners give me there best guess on this. thanks Jim


Senior Member
Re: Truck Airconditioner

Well, I don't know much about air conditioners, but I know a bit about fuses.

If the circuit is designed for a 10 amp fuse, putting a 20 amp fuse in is a Bad Idea. There may be a wire in the circuit which cannot handle 20 amps, and you could burn it up or worse, start a fire.

A fuse blows if more current than is designed to goes through it. This can be caused by a load which is drawing more current than it should (the device is bad or operating outside its design specs), or current is going somewhere it was not intended (something unexpected was added to the circuit or current is 'leaking' to ground (a 'short').

Usually the distribution of A/C within the cab is controlled by vacuum valves, and a hose developing a leak or coming off a nipple is the most common cause of not being able to direct the air.

As for the compressor, the ones I have had go bad made a lot of noise...

C Nash

Senior Member
Re: Truck Airconditioner

Is the heater/aircond fan controled by the fuse? Think you will have 2 problems. One the air not switching to the proper vents more than likely will be in the vacuum supply system or vacuum valves. The fuse blowing will be a short or the fan motor pulling to many amps. If the fuse only controls the compressor you could be low in freon.


New Member
Re: Truck Airconditioner

By what you explaned I would think that the problem is in the dash. Atleast that is where I would start. The controll is controlled by vacume but there is also a switch in the control that turns the A/C clutch on as well as the fan. My guess is that when he worked on it he might have broken something that maybe can't be fixed without replacing the whole control. if you lose all vacume the control goes to defrost for safty purposes. Good luck