Vectra Heater Controls

etchamp · May 25, 2018, 10:28 AM

Been chasing a wiring issue with my 95 Vectra and have finally decided that I may need help

It keeps blowing the HTR fuse within a minute of putting it in. The fuse gets crazy hot before it blows. The fuse will blow at any blower speed.

I pulled the blower out first and I see no issues with it at all and assume the relay would absorb any problems it may cause. It spins easily, makes no noise, and is cool to the touch while running in my hands.

I swapped out the relay with a spare on the heater box and it would still blow the fuse.

I removed the resistor to look it over and it appears as it should.

After looking at the schematics it appears to me that the fuse leads back to the heater control switch on the dash which feeds the blower speed switch...anyone know of a testing method for these or to where i can even replace it with new?

fasteddie313 · May 25, 2018, 01:08 PM

Can you unplug the blower motor close to the motor side and see if it still blows the fuse with no blower in circuit?

It sounds to me like it probably will, and that will mean their is a short somewhere between the relay switched + out and the blower..

Start unplugging stuff from the blower side working towards the relay and test every time..

I would probably pull the relay and put my test light in the relay plug hole on the right pin, put the other side of the test light to +12v, then when you unplug this and that, when the test light goes out, you found your short..

Rickf1985 · May 25, 2018, 06:54 PM

Do you have a rear blower that may be tied into the same circuit? If the front blower is on high it is bypassing the resistor. Just mentioning that so you can use it to eliminate the resistor. Fan controls do go bad but usually as a result of a bad fan overloading the circuit. Like Eddie said, unplug the blower and see if it still blows.

etchamp · June 02, 2018, 11:53 PM

Well...got back on it this week.

Unplugged the resistor, relay, and the blower motor and the fuse was getting hotter as time went on. I pulled the dash apart removed the heater control and blower switch and they both had really dark terminals on two pins so I replaced them both......fuse is still smoking hot with everything still plugged in. Looking at the schematic, there is a light blue wire that comes from the heater control that feeds the low pressure switch, t-stat, and ac clutch....unplug it in the morning and start again.

TerryH · June 03, 2018, 12:26 AM

Quote from: Rickf1985 on May 25, 2018, 06:54 PM
Do you have a rear blower that may be tied into the same circuit? If the front blower is on high it is bypassing the resistor. Just mentioning that so you can use it to eliminate the resistor. Fan controls do go bad but usually as a result of a bad fan overloading the circuit. Like Eddie said, unplug the blower and see if it still blows.

Back to what Rick posted, I had a rear engine heater/blower that used a dedicated dash mounted 3way switch - Rear Heat On/High/Low.
Could that (if you have one) be causing issues?

Rickf1985 · June 03, 2018, 09:17 AM

My rear blower works no matter what position the front switch is in so I doubt it is tied to that switch but I do not know if it is on the same circuit or on it's own, never had a reason to look. You could have a shorted AC clutch but that would only cause problems when you were in a selection that called for AC, Those are defrost, AC, and on some of them the vent setting will run the AC. Heat will not run the AC. There is one wire coming out of the top of the air conditioner clutch that runs back towards the back of the compressor. Most have a plug in the wire so you could just unplug that wire to isolate the AC clutch. I have done that on mine since my compressor is toast.

etchamp · June 03, 2018, 12:17 PM

Removed the blue wire as the schematic shows and the fuse lived....bypassed the stat and the switch and the fuse was still dying so I pulled the dog house off and unhooked the clutch and all is well.

I tested the clutch and it has .4 ohms and im told that 2-5 is in range and everything else is bad so I have a new one ordered. Also noticed that it had battery voltage at the plug but when its connected it takes 7-10 seconds for the clutch to actually engage.

Fingers crossed.

Rickf1985 · June 03, 2018, 06:27 PM

If it has high mileage the it is not uncommon for those clutches to fail. The gap gets to wide from wear and then they start to slip and the heat from the slipping melts the internal wiring in the clutch and you see the end result. A lot of times that flat out go up in smoke.

etchamp · June 03, 2018, 10:42 PM

Believe it or not I bought it with roughly 25K and I've put 10K on it since 2015....but it is still is 23 years old and is slowly showing its age.