Check out our online tech training courses at Master Samurai Tech…

Click here to check out our structured, online appliance repair training courses for rookies and experienced techs.

FAQs | Repair Videos | Academy | Newsletter | Podcast | Contact

Stay connected with us...

Samurai on Facebook - become a fan today! Sign up for our free newsletter and keep up with all things Appliantology. Subscribe to our YouTube channel for lots of appliance repair tips and help! Follow the Samurai on Twitter and get timely morsels of Appliantological Wisdom! Subscribe to our MST Radio podcast to learn secrets of the trade.
bigcrunch

fan does not always work in heat mode

40 posts in this topic

I have a Payne PF1MNA036 that runs on the heat strips\coils no heat pump.

When it calls for heat most of the time fan kicks on and pushes warm air out of the vents. Sometimes the fan does not come on, sometimes the fan cuts off while still on the heat cycle with few degrees shy of where the thermostat is set.

In either non function situation the thermostat has "heat on" the displayed and red LED is lit up on the control panel outside of the air handler that shows heat is energized.

Fan comes on and stays on during all A\C cycles.

Any ideas of where the problem maybe?

Share this post


Link to post
Share on other sites

Need appliance parts? Call 877-803-7957 now!

Does this model have a fan control board or a dedicated fan relay.

How many wires on the fan motor and where are they connected?

Your motor should have a black motor wire connected for high speed for cooling.

It may have a red or blue wire connected for low or medium speed heat.

The lo or med. speeds could be bad or a bad wire connection.

The fan relay could be bad in the lo or med. relay switch.

Your common wire will be white yellow or purple.

Leave it alone.

If red or blue is connected,remove them and tape the terminal ends so they do not short out.

Put the black wire in the terminal the red or blue was in and run the heater and let us know what happens.

Share this post


Link to post
Share on other sites

This unit may also be wired in series with a fan limit switch that must be a specific temperature to activate and de-activate.

If so the limit switch could be bad or a heater limit could be bad.

Attach your amp meter to the system while running in heat.

Each heater will pull about 18-20 amps.

Edited by jumptrout

Share this post


Link to post
Share on other sites

Looks like a dedicated fan relay board.

3 wires come out of the fan, yellow to a transformer, black to relay on control board, blue not attached.

The heat coils are pullign amps dont know how much, wires get very warm.

I'll get some pics of the setup.

Share this post


Link to post
Share on other sites

To properly check this you need 2 meters.

One set for amps and attached to the air handler power supply to read heater amps.

The other set for volts to check yellow and black on the motor at the transformer and the fan relay.

These should be checked simultaneously.

If voltage to the motor stops and the heaters continue heating I would replace the control board.

In the interim you should use FAN ON at the thermostat while in the heat mode to avoid a possible malfunction in the heaters.

Share this post


Link to post
Share on other sites

I'll have to source another meter then.

A couple of itmes to add I replaced the control board and fan motor capacitor.

Something drawing down the amps to keep the fan from starting?

Share this post


Link to post
Share on other sites

Now that you have provided all the information we can start over.

Amp the heaters.

Amp the motor.

Check board power(volts) to the motor.

Check the green (fan) signal at the board from the t-stat.

Verify your re-wiring of the new board to the wiring diagram.

All these have to be done at the same time to find out what is malfunctioning.

Share this post


Link to post
Share on other sites

http://www.harborfre...igital+clamp-on

check the specs ... red "clamp" is OK,

don't get the meter with the "pink" Clamp

(also usually 20% OFF coupons somewhere, even on sale items)

Share this post


Link to post
Share on other sites

That black component in photo 165 is the fan relay. Single stack sequencer. Starts the fan on a delay so that the vents will be warm when the fan comes on.

Share this post


Link to post
Share on other sites

I'll acquire one of the multimeters, I think Harbor Freight will be closed Sunday. So be Monday. thanks for the info.

If a heater coil starts to go bad it can draw to much current and keep other timed devices from starting?

On the single stack timing sequencer the smaller gauge blue wire goes to the control board relay it turns it on for the fan motor?

thanks and Merry ChristmasHappy Holidays.

Share this post


Link to post
Share on other sites

Look at that picture. The limits and heater elements are all orange and yelllow. The fan relay has black wires a goin to it.

Share this post


Link to post
Share on other sites

Hey applianceman18007260692 on the top of the relay stack to the right wires are blue, large gauge goes to heater strip smaller feeds back to the control panel to the relay on it see pic 168 top of the black relay. That one turns on the fan?

Share this post


Link to post
Share on other sites

Here is what I did without the multimeter to test amp draw: unplugged the first stage heat coil, second stage and fan have come on everytime now.

It does heat not as fast when both heat coils are plugged in.

Something drawing to many amps?

heat coil going bad? fan motor?

Share this post


Link to post
Share on other sites

Since you have no meter,hook up all heaters and run them while putting your hand on the breaker in the circuit panel. If it starts getting hot,replace the breaker and re-tighten all circuit wires as well as the ground wire.

Share this post


Link to post
Share on other sites

They use that thing to brang the heat on in stages to prevent tripping the breaker. You want the fan to come on after the elements come on. Not very familiar with these new fangled furnaces with electronics. A simple sequencer could work that furnace without them electronics. I know guys that just yank all that out and a mount a sequencer.

Share this post


Link to post
Share on other sites

I ran it with the 2 heater coils powered and fan, it ran 10 minutes on heat. The circuit breaker is not even warm temp after that duration.

Share this post


Link to post
Share on other sites

Then you still have to check for power from the transformer connection and the fan relay connection when this is happening.

If the motor still has power it will be a bad motor.

What is the amp draw on the motor?

Share this post


Link to post
Share on other sites

Next time it quit put yer hand on the motor if it is hot as heck it could be a bad bearing inside the motor. I doubt if it is the cap since the thang takes off by itself. Capacitors are either gonna be bad (Shorted or open) OR good. No in between.

Share this post


Link to post
Share on other sites

OK here are the test I did with amp meter

heat coil 1

start 16

run 15

heat coil 2

start 17

run 15

fan black wire

start 3.5

run 2.2

fan capacitor brown wire

run 1.75

One thing I did notice with second person at the thermostat once I plugged in the 2nd heat coil I previously unplugged, "heat on" would light up on the thermostat and heat light illuminated on the air handler control panel afixed to the outside of it. But no heat would come on, fan or coils varified with amp gauge. The unit had ran 2 minutes prior with one heat coil plugged in. I unplugged 2nd heat coil again plugged in power breaker set thermostat for heat call and everything turned on.

Share this post


Link to post
Share on other sites

Maybe that bimetal heater inside that relay might be going out but just ain't gave up the ghost yet. The way that dude works is a small coil is mounted inside the thang. It takes a set amount of time for it to heat up sufficiently to turn on thangs. Then when power is removed from it as it cools down it releases components. People used to bring sequencers into my shop for me to check. I noted that taping on the side of a sicking one would release the bimetal. Obviously with all the power going into the thang you go touching the wrong thang you might get lit up. They do not cost that much, but they can sure be a pain in the ass to diagnose sometimes.

Share this post


Link to post
Share on other sites

OK my sequencer is labled as a 15sh4, google'd it looks like there are a whole slew of exchange numbers avail. trying to avoid China what brands are a good choice?

Share this post


Link to post
Share on other sites

The AMP readings I have are within range?

Share this post


Link to post
Share on other sites

What are the amp readings on the heater(s) and the fan motor?

Share this post


Link to post
Share on other sites

Hey jumptrout

amp readings below

heat coil 1

start 16

run 15

heat coil 2

start 17

run 15

fan black wire

start 3.5

run 2.2

fan capacitor brown wire

run 1.75

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now