High Speed Fan on Dash intermittent

[rexabbot]

I have a 1996 Overland Osprey Class A on a Spartan Chassis. It has the Evans Tempcon dash control unit RV218416

and the D32H-19A706-AB resistor.

These parts are very common. The control unit is a Chrysler product Slide Action Control Panel for Dash Heater A/C Mopar part no 55036774 and the resistor is also very common.

I have been battling my dash heat/AC fan on high speed. While driving with the fan on high it will run fine for few minutes and then stop. A couple minutes later it will come back on. Also discovered while driving at night that the light on the control unit goes off also when the fan shuts off. It works fine on the other 3 speeds (doesn't stop). I know high speed takes more amps. I have not found a separate relay for it.

I have changed the fan switch on the controller and the resistor on the fan duct box. No change.

Also when the I turn on the fan on dash the fan on the A/C radiator turns on. I notice that the wiring for the relay for that fan was getting hot and looked burnt. I replaced the relay and the wiring that was burnt and it isn't get hot any more.

The wiring harness on the resistor looks good - doesn't look burnt or lose connectors.
I am stumped as to what else to do. Any idea?

[ahicks]

It sounds to me like you fan's power is being fed through an auto reset circuit breaker. Are you familiar with them?

Prior to getting too far into that, I might be tempted to pull the blower motor and give it a spin to see if there's not a lot of drag on it caused by bad bearings or in the case of one I worked on, a magnet that was dragging on the armature... Either problem can be a cause of higher than normal amperage requirements - setting your breaker into action.

Or your breaker might have weakened with age.... I just hate to see that conclusion made prior to checking the motor. You can really fry up some wire and possibly other components making that jump.....

[rexabbot]

Originally Posted by ahicks

It sounds to me like you fan's power is being fed through an auto reset circuit breaker. Are you familiar with them?

Prior to getting too far into that, I might be tempted to pull the blower motor and give it a spin to see if there's not a lot of drag on it caused by bad bearings or in the case of one I worked on, a magnet that was dragging on the armature... Either problem can be a cause of higher than normal amperage requirements - setting your breaker into action.

Or your breaker might have weakened with age.... I just hate to see that conclusion made prior to checking the motor. You can really fry up some wire and possibly other components making that jump.....

Thanks for the reply! I replaced the fan 2 years ago. Fan sounds good , I haven't spun the fan yet as that would involve taking off the Evans plastic cover of the A/C unit and it is a pain with a lot of screws.

This problem has been there for several years. I bought the MH 3 yrs ago and the previous owner told me he had the problem. There was a fan problem (loud squeeking) prior that is why I changed the fan but the intermittent problem was still there.

Your thought about a resetting breaker is an idea - maybe it got weak with the old fan having problems.

I don't know why I can't find a relay for the fan. I guess they don't put them on every time. Someone in another forum suggested that I add a relay.

[ahicks]

A relay might be a good plan if there isn't already one there? Sounds to me like you're in for some wire tracing practice looking to see if you already have one - unless you can find a wiring diagram in your documentation? That might also lead to the discovery of the breaker's location? Many times that breaker will make an audible snapping noise as they break and reset.

[rexabbot]

I found the schematic for my set up I believed. It is wired like the one on page 2, "Typical Midway and HIgh Performance Stacked Coil Wiring Diagram."
here is the link.
http://www.evanstempcon.com/pdf/scs/...schematics.pdf

It appears I do not have a relay.

I looked for the fuse for the fan today and could not find it.

What would the breaker look like?

Thanks for your reply!

Originally Posted by ahicks

A relay might be a good plan if there isn't already one there? Sounds to me like you're in for some wire tracing practice looking to see if you already have one - unless you can find a wiring diagram in your documentation? That might also lead to the discovery of the breaker's location? Many times that breaker will make an audible snapping noise as they break and reset.

[ahicks]

You can get these in 30 amp as well. You would pull the fuse in any fuse panel using the glass fuses and snap something like this one right in the same place. Something the PO may have done to cure a case of constantly blowing fuses?

Snap-in Circuit Breakers

If you have the newer style fuse panel that uses plastic fuses, a circuit breaker might look like this:

Bussmann ATC Circuit Breakers

These are pretty common as well:

Bussman DC Circuit Breakers