C2 Blower Fan Speed Issues

[Michael A.]

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Thanks,

[Edward J.]

Re: C2 Blower Fan Speed Issues

Mike the switch does not look to good, the contact’s in switch may not letting the right amount of voltage get to motor, I would try to get your hand on a switch that works.or you try to disassembly switch to clean contacts? The 3rd speed on switch should be near battery voltage. I would also check voltage at fuse I have seen the fuse terminals get rusted and cause voltage drop. Use the meter at the terminals because that where you will loose the voltage. Does it have a relay? If so check the electrical connection for sign that it heated up.

[Tom E.]

Re: C2 Blower Fan Speed Issues

Mike,
I have a 67 SB with original switch and fan motor and no A/C. I just went out and measured the voltage at the motor connector and here are the results.

Battery has been on a tender since driving last Sunday. Battery surface voltage is 11.8V and engine off.

Fan speed/voltage
Low/2.6v
Med/5.6v
High/10.8v

Based upon the above I would say your switch is fine and motor voltage appears normal. However this is only a sample of 2 so others may chime in. It’s hard to tell from your video as cell phone mics tend to amplify every little sound however my motor is a lot quieter than yours. Especially in your low speed it appears to me you have a noisy fan motor bearing. When you spin the fan by hand it should be perfectly smooth with not roughness noted.
Tom

[Michael A.]

Re: C2 Blower Fan Speed Issues

Thanks for the measurements Tom. Interesting that your measurements are virtually the same while the battery surface voltage is 1v less. The bigger voltage drop I measured suggests there is more resistance in my circuit. What is your fan speed like on the low setting? Do you feel any air movement? I feel no air movement and I hear the motor turning, but very slowly.

Cheers,

[Tom E.]

Re: C2 Blower Fan Speed Issues

Mike,
I have what I would consider normal air flow in the low speed, I can feel light air movement at the defrost vent or footwell vent. Considering the age of these cars I would expect some variation in voltage drops across the circuits from one car to the other. I guess it’s also possible your have some induced drag from your motor that could be different than mine due to age etc. This would cause your speeds to be slower at the same given voltage drop. My son in law has an air meter for his HVAC business, I could borrow that and give a definitive answer if you think it would help.
Tom
Tom

[Michael A.]

[Tom E.]

Re: C2 Blower Fan Speed Issues

Mike,
Dont know if it will help but maybe spray some electrical contact cleaner in the hole on the side of the switch. Couldn’t hurt and may be worth the effort. Looking at your contacts I don’t see enough to cause a poor low motor speed but it certainly doesn’t hurt to clean them. The one other thing that could cause some differences is the resister on the firewall side of the air box. It limits the current to the blower motor. Also see this other thread on blower low speed.

https://www.forums.ncrs.org/showthre...setting-normal

Tom

[Michael A.]

[James W.]

[Edward J.]

Re: C2 Blower Fan Speed Issues

[QUOTE=Michael Andresen (27410);891194]