HVAC Questions? Ask an HVAC Expert for Answers ASAP
Hello, yes you can get a 5 uf run capacity for the fan motor the voltage rating is important. thats the volts out of the capacitor... it can be very high 370 to 440. try to match what the motor mfgr specifies. you might get by with 370v on a fan motor though (its low torque)
If the compressor doesn't run try using a well insulted screw driver to push the contractor closed, see if it runs.
... in that case...if it runs then the problem is in your control circuit. If it doesn't run, check power to it. If thats fine, kill all the power, triple check that its OFF, then triple check it again.
Then pull the wires off of the compressor and check using an OHM meter to ground...any read at all = bad compressor. then check OHMS C to R, C to S, and R to S. R to S should add up to total reads you get on C to R and C to S
any infinite resistance reads indicate an open internal over load.. if the compressor is cool and the internal overload is open... its toast.
these will be low resistance reads, in the 1 to 7 ohm range each. If thats good and the compressor just hums when you shove in the contactor, check its run capacitor again... if it sparked it was probably OK... (watch out however those can explode)
Do all that and get back to me.
Don't use the 10uf capacitor on the new motor if it calls for a 5uf capacitor. Doing that will cause a greater phase displacement between its windings that it was designed for...it will run, but it will run hot (too warm)..and that can damage its motor windings.
Capacitors are cheap. I would get the 5uf it calls for.
Keep me posted, if we get this 26 year old heat pump running it might be a new world record. 10 years is ancient for a heat pump.. 26 years is unheard of. Its worth going after and if you have managed it...the feat speaks very highly of you.
Hello again...it is good news that you can run the compressor manually.. that means its a controls problem... if you changed thermostats that is most likely where the problem is.. these don't always replace wire for wire... One stat fits everyone these days, but you have to add jumpers etc to make them work and they cover that on their wiring diagram...however... each original system my have anomalies that make life difficult even for a pro, on scene that can see what you have.
we should be able to sort it from here though.
Starting with the blower not coming on...that is actually good news. It points to no power at the thermostat. Check voltage at the 24v transformer, red to white...it should read 24v... if not thats the problem.
If you get voltage at the transformer, use a jumper wire and jump red to green at the thermostat. that should bring the fan relay on... if not its a bad stat, bad relay or wire not connected. Let me know how those checks work out and we will go from there.
Hello, first I notice that time on your question is about to expire...you may want to extend that.
To test the transformer put the meter on V for voltage, not mV, or Vdc, but *Vac' and set it in the mid range, then test it in a wall socket and see if you can see it reading 110 volts or close to it.
If so, you are ready to rock with the meter.
Check across white and Orange and let me know what you get. (should be 24v)
Then check across black and red and let me know (should be 110v)
Hello again, thats not the color code standard but the transformer appears white and orange are the 120v power supply,... if that read was 122v that was close enough.
However in that case the other side, black and red, should have read 24v... instead it read 2.5 which indicates you misread the meter, or the voltage on that side is bad...and indeed,. 2.5 volts where you need 24v would cause the problems you have.
But its unusual to see a partial failure like that... so... lets be sure you are reading the meter right on the 24 volts.. go test it on some other 120 volt sources around the house and see if the transformer reads 1/4 of that scale, or 24 volts...not just 2.5 volts... thats a suspect reading.
Another issue is the color coding..it is the reverse of the color code standards for such wiring...so we need to double checks all of those issues.
Hello again, this is what we call in the controls business a 'hair ball' that is all sorts of wiring cobbled together not following any of the industry standards.
When I run into these in the field I remove all of the affected wire and much of what it connects to, even if that part is standard....out. Then rewire from scratch. That works.
I will 'opt out; of this question, leaving it open for another expert who might be able to assist. I will contact a few directly, If you don't here from someone this morning (Saturday AM) I recommend you call a local technician who can sort this our for you hands on, Furnaces can be significant hazard if not attended to property and this one is need of such help, beyond the wiring issues there are others as well that a technician on site can address,,, make sure you get a good one,, check references beforehand.
Good luck, Phil