No Heat

Many of the chevy based motor homes have a particular brand of HEVAC for the dash. Evans if I am not mistaken and I very well may be mistaken, does not matter however.

They have a problem with the heater control valve, it is a water flow valve and it likes to stick.... Open... When this happens you get the same thing I had pulling away from Church this Noon in my dodge.. I set the AC/Heat control to A/C, set the air flow to Dash Vents, and felt hot air.. (Yup, forgot the temp control it was still set to heat since there was frost on the beast this AM)

With hot water flowing the A/C does not cool, So the Prior owner may have installed a Quarter Turn valve in the heater line.. That is the easy fix.

That is the first thing I'd look for.. then we get to the harder stuff, but check that first.

Next we have control failure.. Since I'm only covering one type of HEVAC, (there are others) I need to know the type of system you have before I can do more.

Another thing to check is that there is a coolant shut-off valve on the inlet heater hose to the heater core to keep coolant from entering the heater core when the air conditioner is on. (Just a little bit of hot coolant can negate the A/C.) On some rigs (mine included) that valve let enough coolant past when it was shut off that some owners (me included) added an additional mechanical valve in series with it to completely shut down the coolant flow during the summer months.

For the most part, your system is probably similar to most automotive heater/AC systems.

Good Luck,

~Rick

BoatBud.....There could be several things going on. I see you live in Maryland. If you're trying to get it to heat up in the cold spell you're having, it may not until it's driven for a 1/2 hour or so and even then may be weak.

You should also listen to see if the door on the heating unit is opening and closing, by listening for it on the interior side of the passenger's dash. Run the engine for a few minutes and then turn it off and manipulate the A/C and heater controls. You should be able to hear the heater door open and close.

I'm not sure if that era coach still used vacuum to open and close the heater door or if it was electronic. My guess would be electronic, which would be built into the actual controls. You also need to get under the hood and see if the heater control valve is opening and closing. It will be the valve with heater hoses running to it. You should be able to see if an arm on the valve changes position from A/C to the heat mode. Sometimes you can take the control arm off of the valve and operate it manually to see if it's frozen (rusted) or not.

If you have a trip planned, you can run the heater in the coach while driving to keep you warm, but the windshield may be an issue.

on our diesel pusher there's valves back by the engine that stop the flow to the dash heat.

hanko wrote:

2oldman wrote:
I don't know.

Congrats thats one hell of a fine answer dude

And yet you think your is better

hanko wrote:
Congrats thats one hell of a fine answer dude

Back at cha.

2oldman wrote:
I don't know.

Same here

2oldman wrote:
I don't know.

Congrats thats one hell of a fine answer dude

Thank you, it does have coolest, that's not the problem. I will check the other things suggested.

The switch or linkage may not be opening the value or just clogged. Heater core may also be clogged. Call some radiator shops to see if they might have an answer to your problem.