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#392432 - 07/19/17 08:10 AM A/ C Blower Switch only runs on high speed
Rich47 Offline
Shade Tree Mechanic

Registered: 02/19/12
Posts: 199
Loc: Connecticut
Had my A/C converted over to R 134A and for whatever reason the selector switch for the fan only runs on high. I cannot regulate the fan speed. But the switch works in the heat mode for fan speed. Anyone have any ideas what to troubleshoot for? Thanks again.

#392438 - 07/19/17 10:31 AM Re: A/ C Blower Switch only runs on high speed [Re: Rich47]
AntiqueMechanic Offline

Registered: 12/02/01
Posts: 9649
Loc: Vancouver, WA

Check with the people who installed the AC. It may be set up that way on purpose.

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#393681 - 08/14/17 03:29 PM Re: A/ C Blower Switch only runs on high speed [Re: Rich47]
novasscott Offline

Backyard Mechanic

Registered: 12/16/01
Posts: 346
Loc: Lindenhurst, Illinois
Rich, Ray is right, go back to the installer. The parts might have some compatibility issues with the circuit board or wiring. See what parts they used.
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#393706 - 08/15/17 01:37 PM Re: A/ C Blower Switch only runs on high speed [Re: Rich47]
dens41 Offline

Oil Can Mechanic

Registered: 01/27/08
Posts: 538
Loc: iowa
Converting a system from r-12 to r-134 should not have anything to do with fan speeds. I would check the wiring to the blower resistor, maybe it got unplugged or moved enough to cause a poor connection.
Dens Chevys 1928 coupe 1941street rod 1947Fleetline 4 door 1949 1/2 ton Pickup 1954 210 4 door 1972 Monte Carlo 2003 Corvette convt..

#393708 - 08/15/17 02:38 PM Re: A/ C Blower Switch only runs on high speed [Re: dens41]
canadiantim Offline

Oil Can Mechanic

Registered: 06/25/07
Posts: 527
Loc: Alberta, Canada
If it worked correctly before it was converted then check with installer.

If this just happened out of the blue it would be a good idea to have a look at a wiring diagram for your car.
Usually the high speed bypasses the resistor board and has it's own circuit so a schematic would be nice to see where it goes. Sometime the resistor board for lower speeds fails but high will still work.

GM's in the 70's also seem to melt connectors if the blower motor was tired so pull apart any related connectors and have a look for any deformation.
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