Temperature Adjust on F53 chassis

Normal. On Motorhomes, unlike Automobiles, they use a simple on off valve, that either stops the 180 degree water thru the Heater core or allows a small or large amount of 180 degree water thru the heater core. Just opening that valve a little causes the heater core to go to 180 degrees. The only way to moderate the temp is to turn the AC compressor on and try to get a medium temp that is good for you. Automobiles, use a Blend door system to regulate the amount of cool and heat coming out the vents. Gas Motorhome systems are 50 years behind the times, unless you have a Diesel chassis or a more expensive Motorhome that has a better system, usually in $200,000 and up motorhomes. Doug

Check to see if the blend door is operating.

If I have the A?C on and want to make it a little less cold, turning the knob just a 1/8th turn causes warm to hot aire come out in about a minute or so.

Just looked under the hood and found what I believe to be the vent control, which blocks or allows outside air to come into the cabin. Where can I expect to find the blend door?

zigzagrv wrote:
If I have the A?C on and want to make it a little less cold, turning the knob just a 1/8th turn causes warm to hot aire come out in about a minute or so.

Just looked under the hood and found what I believe to be the vent control, which blocks or allows outside air to come into the cabin. Where can I expect to find the blend door?

That outside door you found is to allow fresh air in to the Evap and heater core. When you go to MAX AC, that door closes and it recirculates air from the cab interior. THERE IS NO BLEND DOOR. As I stated, Gas model Motorhomes do not have the fancier blend door systems Auto's have. I have and still am working on Motorhome Dash AC systems for the past 38 years. Doug

Use this link for the most common Dash AC systems from your year models. You will notice the various parts, there is no blend door system. Doug

http://www.evanstempcon.com/service_parts.php

Thanks Doug. I find it hard to believe they would put a rotary knob on the control panel and it only acts like a switch???

In the side of the box that contains the outside air vent there is a module with two wires attached to it. There also appears to be a temp sensor going into the box.

Here's what I discovered. It seems that the rod connecting the vacuum motor to the vent door is disconnected from the vacuum motor. I can hear the vacuum motor operate when I turn on the vent, but the door does not open or close. I can open and close the door manually.

This may not be THE problem, but it is a problem I will try to fix.

Need to look closely at your A/C and heater. Many are supplied by the coach manufacturer and some by the chassis maker.
Blend door is normally located inside the rig. It is mounted to the air box.
Blend door

dougrainer wrote:


That outside door you found is to allow fresh air in to the Evap and heater core. When you go to MAX AC, that door closes and it recirculates air from the cab interior. THERE IS NO BLEND DOOR. As I stated, Gas model Motorhomes do not have the fancier blend door systems Auto's have. I have and still am working on Motorhome Dash AC systems for the past 38 years. Doug

Except for Fleetwood, which used Denso HVAC with a blend air door, NOT a water control valve.

Richard

Got the vacuum motor out. The rod was rusted off at the motor as well as the housing itself. Both bolts snapped off when I tried to remove the nuts.

Now to find a single port motor??