If by cap you mean the gasket the inducer blower mounts onto it will not affect the inducer blower speed. The problem is that if the seal isn't proper it will not be able to create enough succion in order to activate the pressure switch

Reggie,
Sorry for the shorthand as such. I meant capacitor. This is required for a single phase induction motor. Creates a lag in the phase of the magnetic field of the windings. This allows it spin. Was wondering if a bad connection would cause a out of phase problem thus less RPM. BTW did you slove your problem yet?

Hmm.. you are talking about the inducer blower? The small blower in the top compartment? As I don't recall ever seeing a capacitor on the inducer on
One of these models.

Yeah mine has the black and white wire plus two brown ones. The Cap is located in the blower section with two brown wires leading to opposite sides of the cap.

Yes you are right sorry that the model where they use the same capcitor... as far as I know the capacitor is not the problem as it is only used in the initial start up of the motor... umm when you pulled the inducer off did you have a look at the gasket? That was my problem and yes by replacing it I solved my problem

Quote:

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Originally Posted by Reggie18

umm when you pulled the inducer off did you have a look at the gasket? That was my problem and yes by replacing it I solved my problem

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I do not suspect that this is my problem. "Background" Furnace is 10 yrs old. Bought the house fall 2007. Furnace worked fine. Problems started this fall on start up worked off and on. Replaced pressure switch. Nope. Replaced inducer motor redid seal with gasket maker. When reinstalling new motor. Blew shop vaccuum exhaust both ways through heat exchanger. Just a bit of soot. Air through drain hoses. Water get to pump through drain hoses and P trap. Nothing blocking exhaust. Cut the pipe in two to be sure. Visual check of the top part of xchanger. Just have to check bottom part. Little more work on my part. Any thoughts, plus where did you get your manometer to measure the vaccuum.

Excuse me, did you say something about soot?

Yeah in the exchanger furnace LPG

Does this model have one pressure switch, or two?

Two and it is the draft one failing to close. Tested by jumping switch and all else is okay.

Is this switch NO or NC?

No

Have you tried running the unit with the hose disconnected from this switch? If not, try it for a few minutes. What happens?

Running the unit without which hose the vacuum hose from the blower to the ps... that will do nothing

My manometer was bought from my local supplier

Soot? Hmm... unusual... well my only thought might be the bottom heat exchanger. You have manny small holes with baffles in them if there is water it means there is a bloccage. At the same time you might as well take all the baffles out to check for a blockage

The switch needs the vacuum to close it in order to run. Which hose this is not clear?

Could the blockage occurred over the summer. The front end of the xchanger is plastic and well mounted(gasket glue) to the metal part of the exchanger. Suspect it is brittle and does not like to be pried on. I seen the metal ends you are talking of. These simply pull out?

A restricted heat exchanger may allow the unit to function with only one switch hose connected. The excessive vacuum would transfer through the cross-over hose. That was my point.

If I remember correctly both switches are individual (one positive goes to heat exchanger cassing and other negative going to inducer)

Yes there are good chances the cassing could be brittle and break

And these baffles do simply pull out but be careful it is thin alluminium which bends easilly

Do you have ac?

Reggie you are correct on the pressure switches. Can blow air or pass water to clean the baffles. I have AC. A frame coil over the exchanger but ac was not used this summer as we had a cool summer.

Yes air will most likelly work if its not a big bloccage and it shouldn't since you actually need speciall brushes which are expensive. If AC was not used than its unlikelly that bloccage occurred during summer unless you were very unlucky and humidity somehow created enough of a temp. change in order to loosen soot. Now when you talked about soot in the exchanger you meen primary (top) or secondary if the later inside or outside?>