Carrier Heat Pump/AC and Fan Does Not Turn On
My Carrier system does not turn on. At first I thought the thermostat might be the issue. I have replaced it and still have no results. As a background, my system had an issue where when I turn it to heat, regardless of the temperature it was set to (i.e. above or below the actual temp), the system would run continuously until I manualy turned it off at the thermostat controler. Ive done a bit of trouble shooting and found that a time delay fuse had gone bad. I replaced it and still the system does not work. I am thinking that it is related to the transformer or a relay switch but Im not sure be certain. When I use a voltmeter from the leads leaving the fuse box going to the transformer to the R wire going to the thermostat I get about 60volts. Is this normal, does this even mean anything. Any troubleshooting ideas would be appreciated. If anyone wants to see photos of the inside of my air handler I can send those via. e-mail. let me know. Thanks Originally Posted by Deanbl2 My Carrier system does not turn on. At first I thought the thermostat might be the issue. I have replaced it and still have no results. As a background, my system had an issue where when I turn it to heat, regardless of the temperature it was set to (i.e. above or below the actual temp), the system would run continuously until I manualy turned it off at the thermostat controler. Ive done a bit of trouble shooting and found that a time delay fuse had gone bad. I replaced it and still the system does not work. I am thinking that it is related to the transformer or a relay switch but Im not sure be certain. When I use a voltmeter from the leads leaving the fuse box going to the transformer to the R wire going to the thermostat I get about 60volts. Is this normal, does this even mean anything. Any troubleshooting ideas would be appreciated. If anyone wants to see photos of the inside of my air handler I can send those via. e-mail. let me know. Thanks I take it this is a heat pump with electric heat strip as back up correct? The reason being it would determin the overall votage. Taking it as a heat pump with electric heat the total voltage should be 220V or 110-115V from each leg. So if you are only puting 60V in to it there is something very wrong. Check all of you high and low voltage connections and report back. Thanks for your response. Yes this is a heat pump with electirc heat. I have 220v line coming in to a breaker switch. From the breaker the line splits into two and ties into the fuse box. There are four fuses, it appears that they are paired where, two get supplied power by one branch from the breaker and the other two by the other line. When I measure voltage across each fuse I get about 110v or so. Therefore, to appears to me that power going to the air handler and through the fuses appear to be correct. Im just not 100% on determine what the next faulty part could be. Any thoughts on where or what else I should check. Do you know how I would check the relays? Originally Posted by Deanbl2 Thanks for your response. Yes this is a heat pump with electirc heat. I have 220v line coming in to a breaker switch. branch from the breaker and the other two by the other line From the breaker the line splits into two and ties into the fuse box. There are four fuses, it appears that they are paired where, two get supplied power by one . When I measure voltage across each fuse I get about 110v or so. Therefore, to appears to me that power going to the air handler and through the fuses appear to be correct. Im just not 100% on determine what the next faulty part could be. Any thoughts on where or what else I should check. Do you know how I would check the relays? You need 120V to the X-former (that is if the X-former is a 120V to 24 V step down, check the data plate)and The red wire coming out of the X-former needs to have 24V + - 10%.What is the voltage coming out of the X-former? This is your controlV to the stat and condenser, circut board, fan relays and such. Check all voltage high and low. 220V maybe a 60amp breaker at the pannel for you electric heat. Ok lets start from scratch. Yes I have 220V going to the air handler. The 220 line comes from my outside breaker to the airhandler where it is wired to a breaker switch. From that breaker switch I have 2 lines (110v each) that are wired into a fuse box with 4 fuses (2 fuses per 100 line). My transformer has a red and black wire coming from the fuse box on one side, and on the other two brown wires. One brown wire is cut and spliced to a red wire that is conected to the terminal where the thermostat wire wire in. The other brown wire is wired into what I believe is a relay switch. When checking for the +-24volt do I check the voltage cross the two brown wires? If so, I will check this when I get home this evening. There are no circuit boards in the air handler that I can find. FYI this is a Carrier model. Also, regarding the 60v, this was what I was reading when I attached the black lead of my voltmeter to the black wire that is comming from the fuse box to the transformer, and the red lead of my volt meter to Red wire that would be heading to the thermostat. Not really sure if it even means anything significant? Yes check the 2 brown wires on the other side of the X-former, It sounds like you are not getting any low voltage. Even though it is a Carrier model it must be an older model, can you tell me how old it is? The brown to red is your hot wire and the other brown is common. THere may be an inline fuse forthe X-former on the low side too. You are correct 110 + 110 = 220. The black wires go to the Primary (220v)side of the transformer. THe brown wires are from the Secondary (24v) side of the transformer. Secondary voltage is also refered to as 24 volt control voltage. Which can really be any where form 18 - 30 volts. The brown wires end up as the R and C terminals in the tstat and outdoor unit control board. Check for 24 volts at those two points. Can you post model and serial numbers? I checked the two leads (the two brown wires) comming off the transformer I must be getting ver, very low voltage. the reading when my volt meter is set to a 10 scale is less than .5 volts. Oddly though whether I change the scale to 50, 250, or 1000, the neadle does not move. i double checked at awall outlet and my meter appears to be working fine. Does this mean my transformer is dead? Should I diagnose anything else before I order a transformer or should I just start with that? thanks for all the help. Dean also, not sure on the age. Most likely its over 10 years old, but it could be older my home is 30 years old. the model number on the air handler is 404s200300. Yes, this means thesecondary windings are open. (burned) just incase look or a small rocker button on the X-fomer.It is an overload protection. Not all have them but itis worth checking 1st. If yours does not have one start with a new X-former. It is more than likey that it is 120V primary-12V secondary and the VA is? Look at it it may be 75 VA As for your AHU I would say it is older, the serial number will tell the age if there is no DOM Was that reading of .5 bounced against a verified 220 between the two blacks on the other side? Not much good with model. 40 is a good start. digit 3 and 4 are suspect incorrect. 40 VA trans may cost 40 to 50 bucks, make sure to include an inline fuse. I did check the two blacks and verified i was getting 220v. Ill order a new transformer and see if that does the job. The transformer is a Carrier OEM Transformer 60 VA P/N HT01AW230. I found one on-sline for about 30bucks. The serial number on the AH is E801159. Ill post back after I swap out the transformer to let you know how it goes. Thanks again for all the help. Its been 30 degrees out for a week and Im looking forward to not having a fire burning all day long to keep the chill out. If not already ordered might look for a 75va with built in circuit breaker. Otherwise inline fuse. While transformers do just fail, be prepared for something to have cause the trans to cook. Serial number E means MAY, 8 means 1978. I did order it already. What amp fuse should I get, 30 amp?.. And which wire do i put the fuse in-line with. The red, black or which of the two browns? Thanks again 3 amp inline fuse, if you already ordered the X-former go to radio shack and buy an inline fuse kit. Splice the fuse in the red wire, low volt side The new trans will be connected to 220 on the primary and R and C on the secondary. Matters not which secondary is R or C. C can also be grounded. The fuse should be in which ever lead you choose for R. 3 Amp is perfect. Be sure to have spare fuses. So i replaced the transformer, wired in the fuse (great sugestion), and wala everything seemed to work... Except, the heat wont shut off at desired temp. And when switched to off the heat and fans stay on... Any suggestions. Dean So new trans w/fuse and new stat, same problem heat on always. Bunch of 3 amp fuses I hope. Just to be redundant, discon W at the stat and see what haps. Then discon W and G at AH in turn and see what haps. I'm thinking failed sequencer and or fan relay. I posted a diagram here: Jarredsdad named 40aq-4w. May not be exact for you (trans wires dif colors) but it should be a good guide. BECAREFUL working aroung live components. OK step 1) I disconnected the W (actually this is W2 on my tstat) and turned everything on. At first the heat did not come on, after waiting 5 min or so, I switched the tstat to heat (before it was just off). The heat came on, but still would run indefinately untill I switch the tstat to off (with the w2 wire hooked up it keeps running regardless of whether the heat is turned on) step 2) with w2 discon and G discon, I have the same results to report as above, step 3) with W2, G, at the AH, I have the same results to report as above,... Hoping we have been talking Heatpump all this time...I think the outdoor defrost control maybe the culprit here. Got a model for that old thing? Also, keep in the back of your mind the outside chance of shorted tstat wires in here somewhere. Im pretty sure this is a heatpump, there are two model numbers on the door to the AH 40FQ90070 and 404S200300 There is a diagram for the thing. I can take a photo of it and send it to you via e-mail if it helps, you can send me an e-mail at ************************** and I will respond with the photo of the diagram. Im not even sure where or how the tstat wires could be shorted, lets hope thats not it. THX I ment the model of the outdoor unit. 40FQ90070 and 404S200300, its 40AQ or 40AS for the indoor. Post pictures on photobucket or something like that for all to view. Pics of the unit not only diagram. So I was thinking that there was a possiblility that something could have happened to my new tstat when the transformer finally went out. So I returned the one I recently bought and exchanged it for the same model. I wired it up and so far both heat and cool appear to be operating properly. The only thing I can firgure is that the failing trans caused my orig tstat to malfunction, then when i replaced the tstat the trans caused that one to malfuncting. For now it looks like my unit is working, soIm in the clear. I appreciate all the help, the savings really helps in these economic trying times. If anything further develops I will let you know. Thank You again your help was very usefull. Dean
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