Furnace cycles, no blower, no heat

Reply

  #1  
Old 11-19-02, 04:04 AM
jimz
Visiting Guest
Posts: n/a
NO HEAT - Tappan forced air furnace

No heat! Need HELP! Tappan SGDF 105D48E7. Traditional FA.
Burner cycles on and off, furnace room warm. Motor relay
never actuates. Shorting G & R at furnace (as a test) kicks
on relay, but motor never starts. Has a 2 position FAN
SWITCH mounted inside furnace, can hear and feel click when moving lever on one side up and down, no click when moving lever up and down on other side.

24 volts seems to be ok thru unit. Any ideas on where to
look?

Thanks,

Jim Z
 
Sponsored Links
  #2  
Old 11-19-02, 05:49 AM
Sharp Advice's Avatar
Admin Emeritus
Join Date: Feb 1998
Location: The Shake and Bake State USA
Posts: 10,440
Received 5 Votes on 4 Posts
Hello jimz. Welcome to the Heating & Cooling forum & our Do-It-Yourself Web Site.

If the fan switch will activate the fan relay but the motor fails to startup, most likely the fan motor is defective. Replacing it should correct the problem.

Be sure the fans blower cage will revolve freely. The blower cage has bearings on each end. If the cage only does not rotate freely, the end bearings could be the cause of the problem. Same may apply to the motor bearings.

The burners are cycling on and off because the interior firebox is reaching it's highest allowable temperature. If the high limit switch did not cycle off the burners, firebox melt down would occur.

Continuous cycling of the burners without cooling off the firebox can create firebox damage. Replace the needed parts asap.

An excellent source for orginal replacement parts is your local retail appliance parts store, the local heating dealers and agents retail part stores. Bring the make, model and serial numbers.

Heating Agents carry replacement parts for almost every heater brand. The locations for the dealers, agents and retail part stores are listed in the phone book.

Resident heating professionals replying within this forum, may have alternate solutions, suggestions, opinions and or test and repair methods. Check back several times for additional replies.

If you need further assistance, use the REPLY button to add any additional information or ask additional questions after attempting the correctional method or methods offered.

Regards & Good Luck, Forum Host & Multiple Topic Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultant & Gas Appliance Diagnostics Technician.
 
  #3  
Old 11-19-02, 07:45 AM
jimz
Visiting Guest
Posts: n/a
<<If the fan switch will activate the fan relay but the motor fails to startup, most likely the fan motor is defective.>>

Moving fan switch levers do nothing except make an audible click.
The motor relay never clicks on, except when I jumper
R-G manually with a jumper. And it just clicks, no motor movement,
nothing. Do you think the 2 lever FAN switch is bad???

Jim Z
 
  #4  
Old 11-19-02, 07:47 AM
jimz
Visiting Guest
Posts: n/a
Furnace cycles, no blower, no heat

<<If the fan switch will activate the fan relay but the motor fails to startup, most likely the fan motor is defective.>>

Moving fan switch levers do nothing except make an audible click.
The motor relay never clicks on, except when I jumper
R-G manually with a jumper. And it just clicks, no motor movement,
nothing. Do you think the 2 lever FAN switch is bad???

Jim Z
 
  #5  
Old 11-19-02, 11:19 AM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Received 0 Votes on 0 Posts
blower

If you know the blower relay did pull in then i would go to the blower. Could be the motor or could just be the capacitor. You have to ring them out and see ED
 
  #6  
Old 11-19-02, 11:28 AM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,988
Received 9 Votes on 9 Posts
jimz:
If the fan relay cuts in, the likely culprit is the motor. To diagnose this you would need to probe the connections at the motor for voltage, or roll the dice and change the motor.
 
  #7  
Old 11-20-02, 12:13 PM
jimz
Visiting Guest
Posts: n/a
Right you are! Many thanks for your help.
I've got 120VAC to motor, but won't run unless I manually
turn the blower to start the motor spinning. Spins freely.
Once running, runs quietly for the duration of the cycle, but
won't restart.

Where is the capacitor located? Where are the lube points
(assuming that my motor is not a sealed unit).

Thanks again!

Jim Z

Moderators Note:
Jim
I merged your two threads into one.
Please use the Reply Button to continue, add additional information or questions to this original question. In doing so it allows the thread to remain intact and easier for all to follow along.
Thanks.
Web Site Host,
Tom_B
 

Last edited by Sharp Advice; 11-21-02 at 06:16 AM.
  #8  
Old 11-20-02, 01:41 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Received 0 Votes on 0 Posts
blower

If it run when you spin its the capacitor, got tobeMost of the time its right on the blower outside some where.Oval can like make sure you get the "volt and the same mfd" on this run capacitor as the old one ok . Now oil if i tell you there there they wont be and if i tell you they are not there they will be. If you do have them look for a little round plug like. They pull out and you can oil them there Use a # 10 not the 3in1 ED
 
  #9  
Old 11-23-02, 02:19 PM
Member
Join Date: Nov 2002
Location: Massachusetts
Posts: 1,819
Received 0 Votes on 0 Posts
capacitors

To see if you have oilers, use a girls compac mirror and a flash light. The oiler plugs SHOULD BE in the upper top third to of the end bells to allow gravity to feed the oil into the bearing wicks on the front and rear bearing. Many of the bearings today are lifetime. Like people, some live longer than others. To find the capacitor, follow the brown wires out of the motor, one will have a brown stripe. This is only if it is a PSC motor. If you had to ask, I suspect it's a low torque, shaded pole motor. If its a shaded pole motor, there will be no capacitor, buy a replacement motor.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: