Gas and Oil Home Heating Furnaces - Blower Motor Capacitor

My renter called me late last night to tell me the AC smelled like something was burning.
I checked the unit out and believe I have the answer.
The blower did not seem to be runing at full speed thus causing it to get hot? I pulled the blower motor to get to the capacitor to check it. Using an anolog meter from post to post the neddle deflects all the way to 0 and stays, the same is true when switching the leads. When checking from post to case there is no meter movement.

The cap. is a mallory 5 mfd 370 vac 60 cycle 32ba3705, 63846, 7331W Which of these numbers is the part number, or can someone give me a different brand PN that I could get from granger.com ? At Grainger the web site give me more info than I know how to relate to my application.

5 mfd 370 vac, that is all you need

How about my trouble shooting? Would you agree that the slow motor is due to the cap?

I doo believe the analog meter won't work unless you switch it to 10K ohm!!!!!! This doesn't tell you if it's in proper range, but if it doesn't move, it is definetly shot. Caps are alot cheaper than a motor....also the speed terminal might be bad, try another speed....also the fan will slow down with the cover off.
:rolleyes:

I had the cap tested with a cap tester and found it to be good. Checked the motor and found it to be the problem.
After a day the renter called and said the house was being cooled better than ever. Only now the fan will not shut off. This time I think the coil is the culpert. When checking the out put of the coil I get 0 volts and no matter which position I put the thermostat in the fan continues to run. What do you think?

it sounds as if the relay contacts are welded shut. replace it. The only other thing would be the thermostat is screweed up or the wiring was miswired. If the coil to the relay is not energized and the fan runs, the relay is fried. If it is in auto and the temp is above room temp by 10F the fan shouldn't run wait a few minutes for the fan to stop, some units try ring out the last drops of cooling.
:p

One thing with rental property, it is like a box of chocolate you never know what you are going to get into and if someone has messed with someything or even that I could have messed things up sometime before and only finding out now.
On with my wooos.... I have so far changed out a burnt out fan motor, fan relay, thermostat and coil. The fan and air are now working normal in the fan only operation and in the A/C auto position, the fan and heat are not coming on line.
If I could read the electrical diagram in the pnl I could check the wiring for the heat system.
Neither the heat coils or the fan come on.
This unit is a Sun Dial model PT 2-03-15-10 SN 53-186017 Can you direct me to an electric diagram for this unit?

gas, electric, heat pump, oil, etc?

These units were made by Square D Company, the same guys that make electrical parts...They've been out of business for years now... FYI...One problem is that if you have a heat pump the reversing valve is backwards, in other words, it energizes to cool. Most of the industry now offer thermostats that will accomodate this problem. You said you replaced the coil, what coil??? Is this a heat pump, or electric furnace? :o

electric heat, this is not a heat pump.
The unit is forced air with electric heat coils and "A" coil with ouside codensing unit charged with R22.
I'm sorry, not a coil but the transformer is what I changed.

If I had a diagram of the wires that controls the heat and turns the fan on in the heat mode I believe this would take care of this.
Thank you.
daniel

I think if you go to the air handler during a call for heat you'll find the power isn't coming in through the W (or W1) wire, Is the transformer a grounded transformer? Not all are. If you have 24V from ground to the R wire, you have a grounded transformer. If you do, you can test ground to W or W1, and should read 24V. Otherwise, you'll have to find the common side of the secondary part of the transformer usually designated C. Most secondarys have a blue and yellow wire.
The whole reason for this, MAY be because you need a jumper from Rc to Rh in the thermostat. Check it out. If the new thermostat has an energy switch or dip switch, make sure you have it on E, or the fan won't start immediately on a call for heat, but rather, a time delay, and this may burn out your thermal fuse safety link.:cool: