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77 Deville A/C Help


ccdog

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Hi guys, I have an issue with my a/c on my 77 Deville that I need help with. The blower does not work but the blower runs when wired direct. A local mechanic told my brother I need a "head controller" or "control head". I have no idea what he is talking about. I am assuming that it is a relay of some sort. Do any of you folks know what he is referring to. If so, what is it called and do you have any idea where I can get one? I have received great info in the past on here for my 77 and 97 so I figured I'd ask here first. Thanks in advance for any info....Jim

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The control head is the climate control panel (with the temperature wheel) on the dash. Those units are available remanufactureed from the dealer at a reasonable cost.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The 1977 Automatic Climate Control (analogue) is different from the later digital systems (introduced on 1980 E/K models).

Does the blower run when the Climate Control is set to 'Defrost'? If so, this suggests the Heater Turn-On Switch, located at the front of the RH cylinder head, is stuck in the open position. When the interior temperature is below ~60 F, blower operation is delayed until the engine temperature has reached ~120 F. Grounding this switch's lead should activate the blower relay.

The next thing to check is the 4 terminal blower relay, hanging under the LH instrument panel area. If there's B+ voltage on the blower feed with the ignition ON, disassemble the centre instrument panel (be careful removing the two air vents) and inspect the main terminal at the Climate Control head. It is possible that heat from a poor connection at either blower circuit wire (12 AWG) has melted the plastic connector, allowing the terminal to back off, resulting in an open circuit.

In any case, the problem should be simple and inexpensive to repair.

___________________________________________________

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