Need Help...Outside unit will not shut off

Hey all....I have a problem with my outside unit not wanting to shut off. I just recently graduated from an HVAC program, but I am stumped as to why my unit will not shut off unless I switch it off of cool from the furnace. For some reason when I switch the thermostat off of cool, the outside and inside units will not shut off. I can turn the temp above the temp in the house so it will kick off, but it wont. I have even turned the switch on the furnace off of cool, and tried to just run the fan in the on position and it will not kick on...the only way I can turn on and off my unit is to use the switch on the furnace.....I am completely stumped as to why it is doing this...I have even went out and check the contactor...and it seems to be working fine. Can anyone help me out.

Bad stat or short in wiring. No detailed troubleshooting in this area of the site. Get 14 more posts under your belt and apply for professional membership and we can discuss this in more detail on a professional forum on this site.

Put the old stat back on.

Ants.

Is it a mobile home furnace and you tried to put a new t-stat on.

Quote:

---

Originally Posted by the dangling wrangler

Ants.

---

Bugs wouldn't cause the indoor unit to operate or wouldn't allow the outdoor unit to shut down by turning off the furnace power. It has to be in the control system.

Quote:

---

Originally Posted by RoBoTeq

Bugs wouldn't cause the indoor unit to operate or wouldn't allow the outdoor unit to shut down by turning off the furnace power. It has to be in the control system.

---

He never said he cut the power off to the furnace.

I never put a new T-Stat on, but yes it is in a mobile home...it is a Coleman Presidential Energy Saver A/C unit and a Presidential III Furnace Unit. The thing is when I have the T-Stat in the off position...the A/C still runs, that is with the Cool switch turned on on the furnace. The only way it will shut off is if I Switch it off of COOL on the furnace. if I turn the cool switch off I can go to the t-stat and try to turn the fan to the on position and it doesnt even do anything....I have even tried to turn it to Heat mode..and nothing happends...the only thing I can think of is a faulty T-stat

I don't remember but I think the t-stat is a 2 or 3 wire t-stat.It is simple to diagnose the t-stat but per rules I can't explain.

it is a simple 2 wire t-stat...I have even disconnected both of the wires, one at a time, and it just keeps on running

O.k. it is in your controls in your furnace.Call a tech.

that is why I came on here...I just recently graduated HVAC school and I am all certified...but still can't figure this one out...never ran across this kind of problem

Get 15 post and apply for pro status.