Is there a way to test a blower motor? - MULTIPLE UPDATES


OK4450 - I checked the ammeter gauge again and it actually looks like an increase from 10 to 30 amps when I go from setting 1 to 4 on the fan. I know those gauges aren’t very accurate but that’s still pretty high eh…so should I replace the blower motor and also get a new wheel or just reuse the old wheel after cleaning it?

Should I grab a new resistor while I’m at it?

I also checked the heater control valve by unplugging the vacuum hose with the heater and fan on, and checking for suction on the hose. I could not feel anything by putting my finger tip on it…is that test good enough to say there’s no vacuum on the line?

And on a different subject, I had posted before regarding rough running when the car was started cold and you gave me a test for the choke pull off…well I had someone press the gas pedal while the car was off and I looked at the carb…I only had the top of the air cleaner off, and while I could hear something mechanical moving underneath the air cleaner, the flap did not move at all, stayed in the full open position. Time for a new choke pull off?

And finally…also re: a previous post on getting the fuel filter changed…well I finally got the fuel line unscrewed from the fuel inlet nut using a large wrench on the fuel inlet nut and a locking wrench on the fuel line. Anyway, that was last night. Today, it was a bit hard to start from cold and now there is some hesistation while driving…it happens when just cruising and then the gas pedal is pressed. It’ll hesistate and then suddenly have power. I watched the tach when this would happen and noticed it seemed to first jump about 200 rpm, then drop back down 200 during the hesitation and then back up approx 500-1000 rpm depending on how hard I was on the gas. This happens in about a half second to a second.

I thought maybe the rain today was causing this, and checked the spark plug wires for arcing tonight, but nothing seen with the engine being revved in the dark.

We did manage to break a valve that has two vacuum lines going from it into the carb when doing the fuel filter…I’m not sure what this valve is called, it’s plugged into a metal part that has the upper radiator hose plugged into it, on top of the front of the engine. Only one of the vacuum line is disconnected, but could this cause this hesitation? Or could a new fuel filter cause this behaviour?

Thanks for reading all that and all your suggestions…really appreciate it.



Just read your other reply, OK…so ignore the wheel question. and when I say the increase is from 10 to 30, I mean an increase of 20 amps, not a fluctuating increase if 10-30 amps…


A 10 amp draw is huge and I’m having a time comprehending a 30 amp draw. That’s almost a dead short.
As I mentioned in the other post, you can reuse the wheel if you get it off without cracking it. Just clean it up as clogged dirt can throw the wheel out of balance.

I would not worry about the resistor at this point. There is usually no in-between on these; the circuit is either good or it’s not.

Just to make sure we’re on the same page about the choke pull-off, the engine must be cranked while inspecting this as it requires manifold vacuum to break it open a little.

My memory is real fuzzy on this broken thermovalve since I have not looked at one of these in a while. Those vacuum lines should either control the distributor vacuum advance, EGR circuit, or possibly the warm air ducting into the air cleaner.
Yes, it could cause a hesitation and wandering idle if it’s sucking air.

As a temporary fix, you could splice the hoses together and bypass the thermovalve until you find a replacement thermovalve. The thermovalves are in place to meet emissions regulations in which ignition advance, EGR operation, etc. is affected during cold engine operation.

Hope some of that helps anyway.


Thanks for all the suggestions.

The ammeter may not be very accurate at all…it normally is at just under the 10 mark without any accessories on, except the radio. Turning on the headlights will bring it up to 30, so will putting the fan on the highest setting. Curiously, putting both the headlights and fan on at the same time only brings the amps up to 35-40…not 50.

Can you explain the choke-pull off test a bit more? I thought the test was the tap the accelerator while the engine was off and the choke plate would close except for about a 1/8" opening?

I will try to repair the thermovalve until I can find a replacement…are these obscure parts best to check with a dealer for?

Thanks for all the help!


All of the lighting and the fan on high altogether should barely draw 10 amps or so.

With the choke pull-off what you want on a cold engine is the choke flap to be completely closed when the engine is off.
Once started, and with the top of the air cleaner off, take a quick look at the choke flap. It should open instantly about 1/8" when the engine starts.
A defective choke pull-off will usually not open the flap at all and this causes overchoking; running rough, belching black smoke, stumbling and even dying.

A little digging and you should be able to come up with the vacuum thermovalve you need. It may be hard to get from the dealer because it would be considered an obsolete item and procuring one might be a coin flip.
I assume something like this is what you need.

I’m not saying those are the ones you need; just pointing out a similarity. Many of these things may look alike but will work differently based on coolant temps and whether vacuum is passed or shut off.


What could cause over-drawing amps? A short somewhere?

Well, the choke flap is in the full open position with the engine off, and the rear 2 barrels are a crack open. They stay that way at initial startup. Is this a bad choke pull-off or something else? I tried playing with the plunger part and it’s hard to move, and I don’t see how it would open up the rear barrels…I can turn the piece that is attached to the choke pull off arm to open the rear barrels but couldn’t move the arm by hand to do the same thing, if that makes sense.

Re: the heater control valve…the one I checked on my car looks a fair bit different than the one shown on RockAuto…is that possible? The part that I checked, believing it to be the heater control valve is in the hose going into the heater core…

Thanks for the other link, that’s perfect! Should be able to match it using that.


I told you not to mess with the fuel filter unless it was causing a problem but did you listen to me? Nooooooooo. Let this be a lesson to all of you overzealous fuel filter changers.


How can a new filter cause problems? How would a dirty old filter function better…it doesn’t make sense to me.


Well I got adventurous and took some photos of the parts I’m dealing with so anyone who cares can have a better idea of what I’m talking about.

Pic #1- View of the hoses running to and from the heater core w/ obstructed view of what I think is the heater control valve.

Pic #2- Close up of the heater control valve.

Pic #3- the thermovalve that was broken (only the top hose connector)…I’ve since fixed it with superglue…hope that holds out.


And finally, the carb…this is how it looks when off and cold. If I press the pedal down, the flap closes leaving about a 1/8" opening. When I then start it, it stays there and slowly opens as the vehicle runs. I noticed the choke pull-off is tight when the vehicle is on and releases when I unplug its vacuum hose, so I think it’s working ok.
HOWEVER…I did notice when revving the engine by hand when it’s still cold, I can give it a bit of gas but if I give it a medium amount, it’ll sound like it’s going to stall, and I can hear a lot of air sucking…if I back off on the throttle it sounds like it comes back to life…now, if I give it a bit slowly and then progress to a lot of throttle, it’s ok. JUST like when I’m driving it when cold and start from a stop sign. I checked all the vacuum hoses, but can’t see any obvious cracks or hoses disconnected. Could it be the carb gasket needs to be replaced or the screws tightened? I feel like I’m getting somewhere now… any and all ideas welcome.


The high amperage draw could be just what I mentioned; a blower motor that is badly dragging. The reason a fuse does not blow is that the lower speeds are fused through a 25 amp fuse and the high speed does not go through that fuse; it goes through a high amperage fusible link and high speed blower relay.

That rusty thing does look like a heater valve, of sorts. It looks to be in pretty bad shape. Don’t worry too much about a new one not looking like the old one. Different suppliers and designs may not mean much; they function the same.

That flap on the rear of the carburetor is not the one I’m talking about. That’s for the carburetor secondaries.
That flap on the front that is wide open should be completely closed if the engine is cold and ONLY if the throttle has been depressed one time.
If you depress the throttle and that front flap does not close then the choke flap is stuck. Try cleaning it with some aerosol carb cleaner and see what happens.
If that flap is stuck open that will definitely cause the engine to fall flat when cold.

Try some of that and see what happens.


That explains a lot and puts my mind to ease regarding the heater valve…it does look pretty rough eh.

Sorry, I meant the front flap is open with the engine off, but closes when I hit the gas pedal once before starting the car (well, it stays open about 1/8"). Then it slowly opens to the full position as it warms up, so that sounds like it’s working. Does the choke pull-off control the secondaries? I see it’s kinda connected to them but by moving it by hand, I don’t see how the choke pull-off would open or close them. I know they only open when you have the throttle wide open, will that happen in park, by revving the engine or does it have to be driving?

I’m getting somewhere now, thanks for your continued help and time.