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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
Satisfied Customers: 852
Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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It's 90 degrees outside. My Olsen furnace-which is 20 years

Customer Question

Hi it's 90 degrees outside. My Olsen furnace-which is 20 years old and the a/c which is 7 years old is giving me a headache. I set the thermostat to 68 and the furnace comes on for 6 minutes then stops? I repeated that 3 times and it did the same thing? Is there something I can do to get me thru this night, it's over 90 in the upstairs?
Submitted: 1 year ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 1 year ago.
Hi I'm Brian and I'm here to help! I'm going to assume you have the thermostat set properly and on cool. Is the cooling working and your furnace is coming on at the same time the cooling is? Brian
Customer: replied 1 year ago.
Yes it's cooling for the 6 or so minutes before it quits
Customer: replied 1 year ago.
Are you there?
Expert:  Brian HVAC Guy replied 1 year ago.
It sounds like it may be thermostat related somehow. I doubt a 20 year old furnace would have confused electronic board in it but it's possible. I would pull the thermostat(s) face off of it and look for skinned thermostat wires. (don't worry this is a 24 volt circuit and won't harm you) At worst, you can remove the wire attached to W on the thermostat(s) and put a little piece of tape over it(them). That should stop the furnace from running and get you through until you can get a tech out or have gotten some sleep and can trouble shoot yourself (with my help if necessary) If you have questions, please reply. Otherwise, please remember to rate positively before leaving. Bonuses are welcome and very appreciated!
Expert:  Brian HVAC Guy replied 1 year ago.
Sorry, I'm not the quickest typist! Thanks much,Brian
Customer: replied 1 year ago.
Hey Brian my problem is not that furnace is running, my problem is it only will run for 6 minutes then shuts off? I could use some sleep tonight I've got to represent my largest client at 9:30 am ?
Customer: replied 1 year ago.
You still there Brian?
Expert:  Brian HVAC Guy replied 1 year ago.
Yes, I am here! Your symptoms and explanation sounded like the furnace was actually running in heat. Sorry for the misunderstanding! You can try removing the thermostat face and twisting the R, Y and G wires together. If the system runs for longer then (it should run indefinitely) you have a thermostat that is most likely defective. If it still cycles that quick you have a deeper problem in the system and it will require a multimeter to check some voltages in the control circuit to locate the problem. Thanks,Brian
Customer: replied 1 year ago.
Hey what's up?
Customer: replied 1 year ago.
My furnace is not coming on just the furnace blower is coming on?
Expert:  Brian HVAC Guy replied 1 year ago.
Are you not receiving my replies? I just replied with a suggested test. This also is assuming your drain overflow switch isn't the issue which I assume it's not since you checked that already.
Customer: replied 1 year ago.
No we didn't get your replies?
Expert:  Brian HVAC Guy replied 1 year ago.
I'm sorry about that, here is what I wrote earlier: Yes, I am here! Your symptoms and explanation sounded like the furnace was actually running in heat. Sorry for the misunderstanding! You can try removing the thermostat face and twisting the R, Y and G wires together. If the system runs for longer then (it should run indefinitely) you have a thermostat that is most likely defective. If it still cycles that quick you have a deeper problem in the system and it will require a multimeter to check some voltages in the control circuit to locate the problem. Thanks,Brian
Customer: replied 1 year ago.
I checked the drain but not the drain overflow "switch" where is it how do I Che k it Brian?
Expert:  Brian HVAC Guy replied 1 year ago.
A drain overflow switch (if you have one) will be installed in a pvc tee in the drain line right near the unit. It will have two wires coming out of the top of a device inserted in the tee. You pull that device out, it will slide up and out, and make sure the float is working and the drain line at the tee is not clogged with gunk.
Customer: replied 1 year ago.
Ok sounds like I can try the 3 wires idea, but do we have to worry if it stays on? For a prolonged time? I mean fire or electrical shorts etc?
Customer: replied 1 year ago.
Ok I'm checking the drain idea thanks
Expert:  Brian HVAC Guy replied 1 year ago.
If it stays on too long, the only thing that will happen is it will overcool your home and the cooling coil may ice up as a result. You can manually control it by turning the power off to your indoor or outdoor unit. If the thermostat is electronic, you can remove the batteries and reboot it. That may help. If it doesn't help and twisting the wires together is the only thing that works then you have a defective thermostat. -Brian
Customer: replied 1 year ago.
Ok thanks
Expert:  Brian HVAC Guy replied 1 year ago.
You're very welcome! Were you able to find a drain switch? If that wasn't it, try the thermostat override above and hopefully that will get you cooling for the night! Thanks much,Brian
Expert:  Brian HVAC Guy replied 1 year ago.
Good luck tomorrow by the way!