HVAC Questions? Ask an HVAC Expert for Answers ASAP
Hello, My name is XXXXX XXXXX I will do my best to help you today.
Is the outdoor unit running?
will check now
it is not running
check the breaker make sure there is voltage to the unit
It could be there is no voltage to the unit, there is no low voltage to the unit, the capacitor is bad, a low pressure switch is tripped.
do you have a multi meter?
ok checking now
there is power to the unit
Do you have a multi meter?
i do but not here. I can get it here. What am i checking?
If there is 240v at the outdoor unit contacts, If there is then you need to to see if there is 24v at the low voltage terminals of those contacts. If there is then you have a bad capacitor if there isn't then you need to to determine if the 24v signal is lost inside from the thermostat or if there is a low pressure switch open. To see if it's low pressure switch you would need refrigerant gages.
OK i will get the meter and check voltage. If ok then I will get a tech as I dont have regirgerant guage.
What you are looking for is if there is 24v between the Common wire and the yellow wire coming into the unit from the thermostat.
If there is then you need to see if there is 240v at the contacts where the high voltage hooks in.
The white and black wire on this one is the line voltage between the two wires you should have 240v
when there is low voltage this center plunger of the contacts should be pulled in. If this plunger is pulled in then there is 24v and your capacitor is bad.
The capacitor is the silver round cylinder on the upper right in this picture. A bad one will sometimes be all swelled up and poped.
If you do not have 24v between common and yellow outside then the signal from the thermostat is broken somewhere either at the furnace or somewhere on the way from thermostat to furnace and then on to the outdoor unit.
question as i was just about to go get the voltage meter. Non of the other 10 units i have are having problems, but when they call for heat the outside unit never comes on. I though that with heat strips the outside unit is not needed?
Also, when I trun the unit down for cool the unit turns on outside and blows very cold air inside.
If you have heat pump systems then the outdoor unit should come on. If you have conventional outside air conditioners with indoor electric furnaces then yes it would only be the electric strips that provide heat.
Is this an apartment?
it is a preschool. Lets assume we have ac units not heat pumps (sorry). I just confirmed all untis aoutside are off but all rooms have heat just the one does not
okay if that is the case then your electric strips are not energizing and you would need to check voltage to them to see if they are getting voltage. If they are then the elements may be shorted out, but chances are it's the sequencer not closing to send full 240v to the element
Where is the strip? Inside the air handler in attic
as is this sequencer
OK. will check
If you are getting 24v between the white and common wire at the airhandler then the thermostat is doing it's job. Then you need to see if the strips are getting the full 240v.
Appears they are gettig the correct amount of volts. Heater kits says model # XXXXX I dont see the seqencer though
You tested at each element and from one leg to the other of each individual element you are getting a full 240v?
Here is what it looks like:
didn't show up.
Here is a better look at what the internal elements look like which you can't see by looking into the furance.
Each little wire element has one leg in and one leg out that form a loop
for a 20kw strips whcih you have there should be 4 sets 8 terminals total
Each set from the leg in across to the leg out should have 240v on it.
each leg will show 120v even if there isn't 240v because of feedbck so you have to test from leg in to leg out. One test lead on in one test lead on out to see if you have 240 being supplied to the element
This is very dangerous and tight so be carefull you do not touch any live wires