Coleman EB15B intermittent auto fan problem
Posted: Tue Jan 25, 2011 2:49 pm
Sorry for this long post, but I want to include any details that might be helpful. My first post on the forum and I have read several similar topics that point to the sequencer, but I would like to be sure.
I have an electric Coleman EB15B. It's a combo unit with the A/C coil on top.
The thermostat is a digital Hunter, about 5 years old. The manual said to leave it set on HG for all furnaces, as long as it would operate the electric furnace correctly, and it has been set that way since installed. (Manual said that HE is only required for certain electric furnaces that won't run under HG.)
A few weeks ago the blower quit coming on automatically, coils were getting hot but no fan. I could turn the blower on manually and it would work. So the repairman came by and the first thing he did was switch the thermostat over to HE. In that setting the fan did kick on automatically, so he tested a few things, said it might be a sticky sequencer, told me to keep an eye on it, and he left. (Didn't charge me anything at least!) A couple hours later after re-reading my thermostat manual, I switched it back to HG, and it was working again on that setting. 3 days later, it quit, so I put the thermostat back on HE, and it fired right up. Again I switched it back to HG after a few hours, and it has been working fine for about 2 weeks. This morning it was back to heating up, but no blower coming on, so I've switched it again to HE and it's working, but please read my concerns below...
What I've noticed and would like some clarification on....in HE it turns on the blower as soon as the thermostat calls for heat. Under HG there is a few seconds delay which allows the coils to heat up, before the blower kicks in. When running under HE, it seems to take alot longer for the house to warm up enough to shut off the furnace. Is it working in HE because it's skipping some important step, making the blower come on as soon as the thermostat calls for heat? Possibly running the fan at a higher speed and not giving the coils a chance to heat the air well?
I found the info in another post for testing the sequencer and these are my readings. I did these tests with the thermostat on HG, coils heating up but blower not coming on automatically.
H1/H2=27.1 vac
H3/H4=27.1 vac
M1/M2= 249 vac
M3/M4= 249 vac
M5/M6= 0 vac
From this I'm assuming I need a new sequencer. I saw in another post to locate the 3 spade terminals on white ceramic bases. I found these I believe just below left of the sequencer (outlined in red in the attached picture). I tried testing them at the same time as the above test (with coils heating but no auto blower working, one probe on terminal, one to metal ground). The readings were 0 on each one, but then seemed to jump to 249 occasionally. Can you clarify if I'm doing this test right, or if I even need to be testing these terminals?
Any help you could give would be appreciated. I'm pretty good with DIY repairs, so if this is something I can fix myself, it would be great to avoid paying a repairman! Thanks in advance!
I have an electric Coleman EB15B. It's a combo unit with the A/C coil on top.
The thermostat is a digital Hunter, about 5 years old. The manual said to leave it set on HG for all furnaces, as long as it would operate the electric furnace correctly, and it has been set that way since installed. (Manual said that HE is only required for certain electric furnaces that won't run under HG.)
A few weeks ago the blower quit coming on automatically, coils were getting hot but no fan. I could turn the blower on manually and it would work. So the repairman came by and the first thing he did was switch the thermostat over to HE. In that setting the fan did kick on automatically, so he tested a few things, said it might be a sticky sequencer, told me to keep an eye on it, and he left. (Didn't charge me anything at least!) A couple hours later after re-reading my thermostat manual, I switched it back to HG, and it was working again on that setting. 3 days later, it quit, so I put the thermostat back on HE, and it fired right up. Again I switched it back to HG after a few hours, and it has been working fine for about 2 weeks. This morning it was back to heating up, but no blower coming on, so I've switched it again to HE and it's working, but please read my concerns below...
What I've noticed and would like some clarification on....in HE it turns on the blower as soon as the thermostat calls for heat. Under HG there is a few seconds delay which allows the coils to heat up, before the blower kicks in. When running under HE, it seems to take alot longer for the house to warm up enough to shut off the furnace. Is it working in HE because it's skipping some important step, making the blower come on as soon as the thermostat calls for heat? Possibly running the fan at a higher speed and not giving the coils a chance to heat the air well?
I found the info in another post for testing the sequencer and these are my readings. I did these tests with the thermostat on HG, coils heating up but blower not coming on automatically.
H1/H2=27.1 vac
H3/H4=27.1 vac
M1/M2= 249 vac
M3/M4= 249 vac
M5/M6= 0 vac
From this I'm assuming I need a new sequencer. I saw in another post to locate the 3 spade terminals on white ceramic bases. I found these I believe just below left of the sequencer (outlined in red in the attached picture). I tried testing them at the same time as the above test (with coils heating but no auto blower working, one probe on terminal, one to metal ground). The readings were 0 on each one, but then seemed to jump to 249 occasionally. Can you clarify if I'm doing this test right, or if I even need to be testing these terminals?
Any help you could give would be appreciated. I'm pretty good with DIY repairs, so if this is something I can fix myself, it would be great to avoid paying a repairman! Thanks in advance!