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Clark's replacement blower problems
Posted by: David Malcolm ()
Date: November 26, 2019 12:32PM

My old heater blower would barely turn on high so I bought the high capacity from Clark's. Got it installed at a club tech session with new hoses. Problem is it only runs on high--nothing on low or medium. Got a "new" used switch from Clark's and stll the same. Tried jumping +12 to the resistor terminals and still the same.
Used the VOM on the resistor and its not "open" but I don't know what the values should be.
My mechanic says he's heard others have this same problem. Any thoughts?

David Malcolm
1969 Monza PG Coupe
NJ near the Meadowlands

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Re: Clark's replacement blower problems
Posted by: Spectre ()
Date: November 26, 2019 12:50PM

Have you measured the voltage at the fan for the various settings?

David Clamp


1965 Corsa convertible - 140 4spd/3.55/AM-FM

2013 Mustang GT convertible - 5.0, 6spd auto, Procharger i-1

2003 Miata SE - 6spd manual (wife's toy)

"Victory is mine!" - SG

Norman, OK

<a href="[www.wunderground.com] src="[weathersticker.wunderground.com]; alt="Click for Norman, Oklahoma Forecast" height="90" width="160"></a>

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Re: Clark's replacement blower problems
Posted by: corventure Dave ()
Date: November 26, 2019 04:07PM

Seems I remember issues with the High Volume electric fan motors and the stock fan switch. I believe this is covered in the CORSA Tech Guide.

For me, I just have the fan switch activate a relay and run the fan single speed powered from the relay. Fan switch off... the engine cooling fan delivers enough air and defrost to maintain. If not I just flip on the electric fan as needed.
The lower fan speeds have never had any real use for me since 1963!

Corventure Dave

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Re: Clark's replacement blower problems
Posted by: 66vairman ()
Date: November 27, 2019 09:10AM

The 69 heater wiring with the heater blower switch on HI by-passes the trunk resistor pack. If both LO and MED don't work it is most likely an open on the resistor pack or the orange wire from the resistor socket to the splice in the interior harness is open. This is assuming the switch is good since you replaced it.

I've found the socket at the heater resistor unplugged and then the fan only works on HI. Same if someone installed a relay as Dave mentioned.

Note the heater LO and MED speed resistors are wire wound and crimped to the terminals. If there is a break DO NOT solder to fix - replace. One resistor is 1.5 ohms and the other is 2.6 ohms for NON air conditioned cars - approximate as no tolerances are given.



Edited 1 time(s). Last edit at 11/27/2019 09:12AM by 66vairman.

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Re: Clark's replacement blower problems
Posted by: David Malcolm ()
Date: November 27, 2019 02:40PM

66vairman
Thanks very much for the info on the resistor values. I used my meter and knew they weren't open but it doesn't really measure that low.
I decided to do proper testing--+12 at each of the appropriate terminals on the switch. Disconnected the cable from the resistor block and have the correct +12 on each of them with the proper switch settings. Plugged in back in an left it on medium for a few minutes and the resistor block gets slightly warm--should indicate the the wiring to the blower is present but still no fan. I'm guessing that the resistance/inductance of the new blower is very different from the original. As you can appreciate using a resistor voltage divider is OK but doesn't take to changes.
At this point I'll use the high speed to get the defroster to work as that's what started this project.
Thinking about using PWM module to get lower speeds, I'll post how that goes.
Thanks again.

David Malcolm
1969 Monza PG Coupe
NJ near the Meadowlands

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Re: Clark's replacement blower problems
Posted by: 66vairman ()
Date: November 27, 2019 07:14PM

David - The blower motor should be a PM102 and requires you to move the old blower cage to the new motor. Sometimes folks use the wrong motor PM134 which fits, but is for the A/C front blower and BTW turns in the opposite direction and draws more amperage.

I've never had an issue with the PM102, but of course anything new can be defective. If the fan works on HI and doesn't blow the fuse that would be a good indication it's fine.

It doesn't take much resistance to cause the blower motor to run very slow. As I mentioned the wire wound resistors are crimped to the connectors and they can corrode. Also the plug terminals and terminals on the resistor board do corrode.

The easiest way forward is to borrow a resistor assembly from another Corvair and DO install it before running things as they get HOT on LO and MED. If that works I'd replace your resistor assembly. Darn difficult to fix them.

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Re: Clark's replacement blower problems
Posted by: Frank DuVal ()
Date: November 27, 2019 07:52PM

You have a VOM, so what are the voltages at the heater resistor terminals (all three)?

I have installed quite a few of the "high volume" blower motors and they are plug and play.

Why would anyone design and build a PWM circuit when resistors work?grinning smiley

The fact that the resistor got "slightly warm" when the switch was in medium speed indicates not enough current is flowing, as the resistor should be close to red hot! That's why it is in the air stream, as 66 says.

Maybe you should read the voltage at the motor with it in high speed to see if there is excessive resistance in the feed wire.

Frank DuVal

Fredericksburg, VA

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Re: Clark's replacement blower problems
Posted by: joelsplace ()
Date: November 27, 2019 07:59PM

The PWM would save a lot of power.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Clark's replacement blower problems
Posted by: David Malcolm ()
Date: November 27, 2019 08:03PM

Got the correct cage from Clark's also. I'll try cleaning the contacts and etc. Also see if I can get another resistor block to try.
Thanks for the info about how hot it should get, I could hold my fingers on it after about 5 min so that doesn't sound right. Its not open, that I can get from my meter. Had slightly over 12VDC going to the block, I'll make some test leads to measure what is coming out.

David Malcolm
1969 Monza PG Coupe
NJ near the Meadowlands

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Re: Clark's replacement blower problems
Posted by: joelsplace ()
Date: November 27, 2019 08:23PM

Don't forget no load voltage doesn't mean much.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Clark's replacement blower problems
Posted by: 66vairman ()
Date: November 27, 2019 08:57PM

David - Darn I forgot to mention that if the ground at the blower motor is not good (adds resistance) the blower motor will run slower than normal. BTW I've fixed a few blower motors that ran slow just by fixing the ground. It's a poor design as the blower motor must ground thru the blower housing, then the two heater box halves, a bracket, and finally to the body - what a complex ground route through a number of bolts and screws that are now decades old and corroded. Excess ground resistance can reduce the amperage to the blower motor considerably.

I run a wire (same gauge as supply or larger wire) with soldered terminals from the blower motor flange to the to the bolt that attached the heater assembly to the body. Note the motor flange screws to the blower housing MUST BE CONDUCTIVE, not the black anodized type (black anodize is an insulator) that Clarks sent me - and I threw into the trash!

The wire to the heater is larger than most in the Corvair and if it is damaged it could add resistance. As Joel said you have to check it connected to the fan motor with the power on - not easy to do.

Good luck.



Edited 2 time(s). Last edit at 11/27/2019 08:58PM by 66vairman.

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Re: Clark's replacement blower problems
Posted by: American Mel ()
Date: November 27, 2019 09:04PM

Frank is correct.
They get REAL HOT ! ! !
DO NOT TOUCH THEM!
It has been a long time ago, and I don't remember why I did it, but I do still remember how much it hurt ! ! ! grinning smiley

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, '62 Monza Wagon, '63 Spyder, '65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dualy, approaching 400K
17'Terry

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Re: Clark's replacement blower problems
Posted by: David Malcolm ()
Date: December 07, 2019 09:54AM

Borrowed a resistor block from a club member today. Installed I get no fan on low, a very slow fan on medium and high on high.

If I jump the block to put the two resistors in parallel I get a medium speed. Ohm values for the block are 2.5 and 1.5 ohms, in parallel about .9.
It looks like the new blower has a different current draw than the original and the resistor/voltage divider circuit just has the wrong values for the new fan.
I might just permanently install the jumper to parallel the resistors and live with a medium and high speeds. Its not easy to find high wattage resistors in these low values and working with nichrome wire as used in the factory part can't be soldered and is brittle.
Ultimately it looks like a PWM circuit might be needed.

David Malcolm
1969 Monza PG Coupe
NJ near the Meadowlands

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Re: Clark's replacement blower problems
Posted by: RexJohnson ()
Date: December 07, 2019 10:04AM

If you are not getting all of the speeds you have something wrong with the wiring. Myself and hundreds of others have installed these new fans and everything works perfect. You do not need to reinvent the wheel to get all of the fan speeds. I would unplug the fan motor and hook up a test light to the wire and see what the light does for each of your speeds. If the light doesn't come on for all of the speeds then start probing with the test light to see where the problem is.

RJ tools
Salem,Oregon

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Re: Clark's replacement blower problems
Posted by: Lane66m ()
Date: December 07, 2019 12:30PM

HS to be grounding issue. I have the hi flow fan with no issues with getting proper speeds. A bad ground will slow down fan.

Al Lane
Ellabell, GA 31308

1966 Monza Coupe, 110 hp, 4 Spd
1966 Monza More Door 110 hp, PG
1968 Camaro SS Coupe 350 CI 295+ hp PG
1964 Greenbrier Deluxe, 6 dr, 80 hp car engine, PG
1947 Farmall A tractor 15 hp


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Re: Clark's replacement blower problems
Posted by: David Malcolm ()
Date: December 07, 2019 12:52PM

Its cold and I don't have garage space. A ground was installed by the club at the install tech session but as I seem to be getting correct voltages out of the switch and into the resistor block and it does blow on high that would be the next thing to check. Just need to wait till its warmer to lie in the driveway and check it.

David Malcolm
1969 Monza PG Coupe
NJ near the Meadowlands

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Re: Clark's replacement blower problems
Posted by: 66vairman ()
Date: December 07, 2019 07:59PM

Dave - Did your old fan only work on HI?

A new PM102 fan motor will blow a LOT of air on HI. If not, then you may have a bad new motor, wiring issue, ground issue, and sometimes the fan rubs on debris or the housing.

I often have folks bring me fan switches (even NOS) that don't work well. The switch contacts are lubed with a dielectric grease that is now dried out and that can result in excess contact resistance.

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Re: Clark's replacement blower problems
Posted by: Frank DuVal ()
Date: December 07, 2019 09:04PM

Quote
David
Ultimately it looks like a PWM circuit might be needed.

No!

Take a break, sit down, have a beverage (Tea?). 2 million Corvairs were built. None had PWM circuits to control blower speed. Clark's has sold unpteen high volume heater blower motors in the last 30 years. I've installed at least 20 myself.

No ONE has had to build a PWM circuit to make the blower work properly.

You are missing something in the wiring.

And therefore, building a PWM circuit will just produce another non-working system! Waste of time.eye popping smiley

Not saying a PWM circuit is a bad idea, they will control speeds without just creating heat as a way to lower speed like resistors, but saying it will not fix your current (hmm, a pun?) problem.winking smiley

What is the current draw with the switch on high? What is the voltage at the blower with the switch on high? And same two questions at the other two speeds. Need data.

Frank DuVal

Fredericksburg, VA



Edited 1 time(s). Last edit at 12/07/2019 09:05PM by Frank DuVal.

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