2003 Bounder Dash A/C Switch Problems (?)

It most likely lost it's refrigerant charge. They have a low pressure switch which won't allow the compressor to come on if there is no charge. You didn't say that they checked for that.

The dash switch being the issue is doubtfull. more likely is a lack of freon or a pressure switch failure. When the compressor was turned on with the TECH2(thru the OBD2)did it come out cold? This would eliminate a low charge. My guess is a shop would have checked the charge tho. Next is to test the switches by removing the plug and using a paper clip between the 2 terminals completing the circuit. There will be a high and a low pressure switch and either could be the problem. If the compressor comes on you have your problem nailed. If there are more than 2 wires on the switch that usually means the switch is can bus data and this test won't work, but on a 2003 i doubt that would be the case.

as stated low Freon. When the compressor comes on when testing does it cool. If you have a gauge set, have you check the pressure. Also if the low pressure switch is bad it won't come on either. You can unplug the wire from switch and jump it. If compressor comes on you found it. If wiring , its going to take a while to check it out. Is this a Evans Tempcon system.

Sorry, but freon is OK. Several shops (in addition to myself) have verified that the cooling system works (though not yet how well it work). Need to get the compressor on enough to really test the freon. The whole issue with pressure switches was checked way before the possible switch issue came up. Figured that was a given when I mentioned that a couple of shops had checked that out.

Not sure what an "Evans Tempcon" system is.

This is a vanilla Chevrolet 8.1L workhorse chassis.

stoshb wrote:
Sorry, but freon is OK. Several shops (in addition to myself) have verified that the cooling system works (though not yet how well it work). Need to get the compressor on enough to really test the freon. The whole issue with pressure switches was checked way before the possible switch issue came up. Figured that was a given when I mentioned that a couple of shops had checked that out.

Well not saying I don't believe you but, was a gauge set installed and what were the pressures? I've seen too many vehicles over the years have this exact issue...

Steve H.
HVAC System Engineer - Chrysler Group LLC.

Evans Tempcon is who makes your Hvac system. They also make mine in my F53 Ford chassis. Apparently, they use the factory compressor and a few other small components but the bulk of the HVAC system is aftermarket. As for the pressure switches, how do you know? Just because you forced the compressor on doesn't mean they are ok. I can't think of any way to test them other than the way i mentioned. As for the dash switch, if you are sure that may be an issue why not test it before you buy a new one? Use a DVM and test current going thru it. You also should be able to jump that switch to get the compressor on if it is bad...

I watched a technician put hoses on both the low and high pressure connectors on the AC system. Don't remember exact numbers, but both values were appropriate for a full system, without the compressor running. This tech then shorted the low pressure switch and nothing happened. His verdict was to replace the compressor, but because of its location, did not want to have any to do any more work.

Second technician, did same test, though I did not witness the pressure checks, and then he went further and tried to force the compressor to come on. I am not sure what wires he used to make this happen, but were related to the engine electronics. In his testing he kept thinking that there was something wrong with either the computer or the switch, but parts issues stopped him from going further.

Third technician also discovered issue with one cylinder misfiring and wanted to blame the computer. However, after more investigation found a bad wire, replaced it and the misfire went away. He now thinks the computer is OK, and, at over $700, really no one is prepared to throw away the computer until we are positive. He is leaning toward the switch being the issue.

I don't have physical possession of the unit right now, but should get it back tomorrow. Love the suggestion to just test it with a voltmeter and will do that first thing when I get it back. While I am hearing trained people point to the switch, I just think there is something else there near the switch that is causing the problem. Just wondering what else might be there.

Had not heard the name of of the company that actually made the other AC parts. Mistakenly thought that they were GM. But then no one company makes all the parts on anything. Had already figured out some of the parts were sold by Fleetwood so they wouldn't be GM parts.

There are several fuse in the system. Two fuse are behind the access panel on the passenger side along side the motor, there are a couple of switches. One fuse between the switch and then fan. A couple in the fuse box under the hood in the front. Found out about these fuses when the fan motor went bad.

To Test the dash switch... You need, a 12 volt light and socket.

Step 1, Find the leads to the switch, Using either a test lamp or a voltmeter find the HOT lead. (The one that is live when the engine is running even if the switch is set to OFF)

now find the line to the refrigerant compressor clutch (likely to the computer)

Hook your lamp to this line and ground. (or better yet, hook two identical lamps, one to hot, one to this lead.

With the switch in the AC position there should be no noticable difference in teh lamps.

If one is bright, the other very dim or not lit.. Bad switch