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Dash HVAC Fan Doesn't Work - Troubleshooting Guide

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05-18-2011, 01:11 AM
Rusty
Dash HVAC Fan Doesn't Work - Troubleshooting Guide
When I started the coach on the last morning of my recent trip, the dash blower wouldn't work on any of the settings. Had the window open until I refueled. Started the generator, and the fan worked for literally a second and then stopped again. Just ran home on the roof A/C.

Today I had the chance, so decided to troubleshoot.

Tools needed:
#2 Phillips Screwdriver
#2 Robertson (Square bit)
1/4" Flat blade
VOM (Volt-OhmMeter - or multimeter)
Jumper wire at least 8'

Please read through all steps before proceeding.

1. Remove the dash hatch. Check the 15A fan fuse if located there. On Regencies, this may be in the electrical compartment. (NOTE: The A/C compressor clutch is on a different (30A) circuit.)

2. Remove the two screws holding the dash control in. NOTE: Grab the nuts so you don't lose them, but DO NOT yet remove the screws. Reach in and locate the spacer between the dash and the HVAC control, grab each, and remove the screw. The control can now be moved carefully forward (towards the firewall) and rotated up into the hatch opening.

3. Disconnect the switch connector. This is T-shaped. The output to the fan is the upper left.

Connect the jumper wire to a known good ground, turn the ignition on and the control button to any except "Off". There should be 12 VDC at the other 3 terminals of the plug, which are connected to each of the 3 speed resistors.

Turn the ignition off.

The way the speed switch works is that there are 3 resistor coils inside the fan housing (installed there for cooling by the airflow) The switch directs the power from the appropriate resistor to the fan motor. The resistors are bypassed for "High" speed. Because there's no current flowing when you make this test, full voltage will appear at the switch connector.

4. Check the switch for continuity with the ohmmeter; connect one meter lead to the tab corresponding to the dead connector, and check each of the other tabs at the corresponding switch position.

5. Remove the cover on the lower dash passenger side. The blower motor should be accessible. There is one spade terminal (from the control panel switch). There may also be a ground wire attached to one of the 5 mounting screws. Turn the ignition on. Remove the wire from the spade and check for 12 VDC. Turn the ignition off.

6. Now remove the ground wire, scrape the crud off the blower motor mount,and reattach. This was the actual problem, so you could have checked this first! Mad But we've had fun, right? RIGHT? mechanic Shields Up


Rusty


MilSpec AMG 6.5L TD 230HP; built-to-order by Peninsular Engines:  Hi-pop injectors, gear-driven camshaft, non-waste-gated, high-output turbo, 18:1 pistons.  Fuel economy increased by 15-20%, power, WOW!"StaRV II"

'94 28' Breakaway: MilSpec AMG 6.5L TD 230HP

Nelson and Chester, not-spoiled Golden Retrievers

Sometimes I think we're alone in the universe, and sometimes I think we're not.
In either case the idea is quite staggering.
- Arthur C. Clarke

It was a woman who drove me to drink, and I've been searching thirty years to find her and thank her - W. C. Fields
05-27-2011, 09:36 PM
Rusty
Redux

Headed over to the Cagles' yesterday, I stopped at the Walmart enroute. Started up the coach, and...no dash blower.

Today I found the real culprit: The hot wire connector on the fan housing was intermittent.

I bought a similar replacement assembly from NAPA, but it didn't quite fit. Since the hot lead goes to one of the brushes, I removed the brush holders and bracket from the new motor and installed it into the old motor. Works fine.

But what I should have tried first is to replace the male spade connector on the hot terminal; that probably would have repaired it... Mad


Rusty


MilSpec AMG 6.5L TD 230HP; built-to-order by Peninsular Engines:  Hi-pop injectors, gear-driven camshaft, non-waste-gated, high-output turbo, 18:1 pistons.  Fuel economy increased by 15-20%, power, WOW!"StaRV II"

'94 28' Breakaway: MilSpec AMG 6.5L TD 230HP

Nelson and Chester, not-spoiled Golden Retrievers

Sometimes I think we're alone in the universe, and sometimes I think we're not.
In either case the idea is quite staggering.
- Arthur C. Clarke

It was a woman who drove me to drink, and I've been searching thirty years to find her and thank her - W. C. Fields