Tempstar 80% 14yr old blower problem

autocruise · 02-28-2010, 11:52 AM

have 14 yr old tempstar lemon. Lots service calls over the yrs. Present problem cycles on normal runs app. 2min blower stops burner keeps burning. when limit switch trips burner shuts off blower comes on. Couple min later burner relites 1min later blower stops until burner shuts down on limit sw. Changed timer board worked ok 14hr started doing same thing.

plummen · 02-28-2010, 11:57 AM

is the motor overheating and kicking itself off? maybe time for new motor and cap

yuri · 02-28-2010, 11:58 AM

Is the motor getting blazing hot when it stops the first time? Carefully touch it with your hand. If so you may need a new motor capacitor and possible one winding in the motor is failing. That being the heating speed, when the limit trips, the board energizes the fan to cool the furnace and it may use a higher speed (good) winding. If the furnace has a HWell Gas valve SV95*** it is nothing but trouble and I would start investing my $$ in a new furnace. Google "smart gas valve" for more info. The heat exchangers fail a lot on that brand also. Sorry.

autocruise · 02-28-2010, 12:10 PM

NO. forgot to mention if i turn t-stat to blower on all time furnace cycles on and off when heat is called for . Blower runs constant of course. just replaced stupid valve after 1st control board.

yuri · 02-28-2010, 12:41 PM

Sounds like your motor is going. Has 3 or 4 windings. The heating one may be faulty. Turning the fan to ON may energize the cooling speed. When the heat cuts in the board stops the fan to allow the heat ex to warm up. Check the heating speed wire connection at the board. May be loose and need a new stakon. 14 yrs is average for any motor. Try using a different speed wire on the heat terminal temporarily to see if the problem goes away. If it does then I am right.

plummen · 02-28-2010, 12:42 PM

when you turn the fan switch on stat to on that brings on the high speed of the blower,same side as cooling.heating side runs on low speed

autocruise · 02-28-2010, 06:42 PM

Thanx for replays moter replaced 3yr ago did amp load 4.6 run 10.2start
on normal setting not on run all time.

yuri · 02-28-2010, 06:46 PM

Did you replace the capacitor when you replaced the motor?

hvaclover · 02-28-2010, 08:51 PM

I am seeing a bridge.....

autocruise · 03-01-2010, 06:16 AM

Yes we did replace the capactior.Will try switching speed wire today. Sorry hvaclover no bridge here just trying to fix furnace.

autocruise · 03-01-2010, 04:38 PM

Switched fan speed wire sofar running properly. Will run this way couple days if it stays working i will replace motor. Thanks.

hvaclover · 03-01-2010, 04:46 PM

Usually the premonition of a bridge hastens repairs for some reason.