carl mc9 (66.144.52.102)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 10, 2002 - 11:05 am: | |
I am still having problems with my air conditioner/heater relay. When the switch for the bus heat / air conditioner is in the middle position the heat light stays on
if I flip the switch up to air conditioning and the temp dial to cooler I get full heat.
If the switch is in the middle position and the coach is at idle, the heater relay found i the compartment under the drivers window flips on and off. The coach is a 1979 mci 9. It worked ok about a month ago.
thanks for any help you can give me
carl mc9 |
Jim Nelson (166.90.108.147)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 12, 2002 - 9:36 pm: | |
Your thermobulb or heat relay might be bad. The thermobulb is a mercury thermometer with a heater coil to adjust the temperature set point, and two contacts in the glass. If the thermobulb or any of the contact wires break, then the bus will never think it got to temperature, and will keep on heating, no matter how hot it gets. Another possibility is that a diode on the heat relay base circuit board has shorted closed - that will also cause a full-heat condition. If you have already had the old-style mercury thermobulb relaced with the electronic one, then you need to cut the black wire on the heat relay base - it will make the temperature control erratic. Honestly, it sounds like the heat relay base - without getting my hands on it, I couldn't know for sure, though. |