HVAC Blower motor / heater box switch advice?
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HVAC Blower motor / heater box switch advice?
Looking for input regarding a problem I'm having w/ the HVAC system on my '78 XJ-S
The problem is when I turn the fan control ON the fan runs for a few minutes and then shuts off and when it shuts off it takes the radio with it also; the system will often come back on after a few minutes.
Yesterday it actually ran for approximately 30 minutes without shutting off and then again seemed fine this morning driving to work; upon running an errand about an hour after arriving at the office both the fan and radio would not come on. NOTE: Radio is an aftermarket where the previous owner had installed by Circuit City back in '88 - car also has the SBC swap via a John's Cars kit; all gauges and everything else works fine.
I have been speaking w/ Gary @ Jag-Aire and suspecting either a bad ground OR possibly a faulty servo or amplifier; I do have the manual control from Jag-Aire to install but waiting on a revised connector to hookup.
Recommendation is to trouble shoot the servo & amplifier by jumping the two wires on the temperature switch apparently located on the heater coolant pipe on the left side of the heater box.
Anyone here able to direct a novice regarding best procedure to locate and access this switch in order to test?
The problem is when I turn the fan control ON the fan runs for a few minutes and then shuts off and when it shuts off it takes the radio with it also; the system will often come back on after a few minutes.
Yesterday it actually ran for approximately 30 minutes without shutting off and then again seemed fine this morning driving to work; upon running an errand about an hour after arriving at the office both the fan and radio would not come on. NOTE: Radio is an aftermarket where the previous owner had installed by Circuit City back in '88 - car also has the SBC swap via a John's Cars kit; all gauges and everything else works fine.
I have been speaking w/ Gary @ Jag-Aire and suspecting either a bad ground OR possibly a faulty servo or amplifier; I do have the manual control from Jag-Aire to install but waiting on a revised connector to hookup.
Recommendation is to trouble shoot the servo & amplifier by jumping the two wires on the temperature switch apparently located on the heater coolant pipe on the left side of the heater box.
Anyone here able to direct a novice regarding best procedure to locate and access this switch in order to test?
Last edited by CZSteve; Jul 14, 2020 at 10:16 PM.
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From cold, the fan will run for a few seconds in all cases with the Delanaire mark II and then stop. It will start again when the system detects that the water is hot enough in the heater matrix for the blend system to work.
It looks to me (from afar!) that the radio is somehow wired into a heater fan wire; it should e completely independent. I your position I would remove the radio and see what it is wired to, then deconnect it and see if the fans work as they should. If they do, wire the radio properly (ie. to lives and earths that are 100% independent of the HVAC wiring..
It looks to me (from afar!) that the radio is somehow wired into a heater fan wire; it should e completely independent. I your position I would remove the radio and see what it is wired to, then deconnect it and see if the fans work as they should. If they do, wire the radio properly (ie. to lives and earths that are 100% independent of the HVAC wiring..
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Recommendation is to trouble shoot the servo & amplifier by jumping the two wires on the temperature switch apparently located on the heater coolant pipe on the left side of the heater box.
Anyone here able to direct a novice regarding best procedure to locate and access this switch in order to test?
Anyone here able to direct a novice regarding best procedure to locate and access this switch in order to test?
Bypassing this switch just eliminates one possible fault, but it's a start.
I agree with Greg's thoughts on the radio
Cheers
DD
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