heat pump questions

[r-mallis]

just recently moved in and never had a heat pump before. i have 2 trane units that are approximatly 15 years old. my upstairs unit seems to work fine all of the time but on my downstairs unit the outside cooling fan comes on and shuts off when it wants to. i understand from reading other threads on this site that the fan shuts off in defrost mode but i dont think my unit is going into defrost when the fan turns out. for example...sometimes when i turn the heat on the compresor will kick on but the fan wont turn on. it will sometimes take up to 15 minutes to kick on. some times i will turn the heat on and the fan will kick on and then shut off after 5 minutes and the kick back on a few minutes later. on the other hand my upstars unit fan never shuts off which is why i think i have a porblem with my downstairs unit. any info on this sitiuation would be greatly appreciated, by the way i know its not the fan motor because i just had it replaced. and when the fan is on the heat works very well...puts out about 90 to 100 degrees out the vent depending on how cold it is outside

[Grady]

Some heat pumps shut off the outdoor fan when the temperature is below Xº. Some others will cycle the fan based on the temperature of the copper tubing on the outdoor unit. Still others cycle the fan based on pressure. Call a local Trane dealer, give the model # of your unit & ask if this is normal. Some of these controls are optional & may or may not be installed on your equipment. The dealer may have to come out & look.

[r-mallis]

i still dont see why the fan would not kick on when i first turn the heat on in the morning and its only 45- 50 degrees outside. it timed it and it takes appoximatly 15 minutes for the fan to kick on when you first turn the unit on. until then im only getting like 80 degrees out the vents, which doesnt do much except waste electricity.

[mattison]

Are you sure the compressor outside is coming on when you 1st turn it on without the fan?

[Ed Imeduc]

by the way i know its not the fan motor because i just had it replaced.

Can it be the defrost board are is the new fan motor wired in right???

What does it do if you go to AC ????

ED ;)

[r-mallis]

yes i am positive the compresor kicks on without the fan when i first turn the heat on. im pretty sure its not going into derost neither because i dont see any steam come out when the fan does finally kick on. i have not tried it with ac yet but i will and i will let you guys know the results. there has to be some kind of relay somewhere that controls the fan i would think. i was thinking that could be my problem.

[Grady]

The fan is usually powered from the contactor via the defrost board & relay. Sometimes there are additional fan controls. See my previous post re: these other controls. Your system may be working the way it is supposed to. BTW, when the motor was replaced was the capacitor replaced too? It should have been.

[r-mallis]

yes the capacitor was replaced with the motor. ok so my heat just kicked on a few minutes ago and i could tell the fan was not on by the cooler air coming from the vents. i switched the t stat to ac like you guys suggested and i heard the outside unit switch from heat to ac but still no fan. i am fairly convinced that if the fan relay is in that defrost board then that is most likely my problem. if anyone else has any suggestions please let me know. thanks to everyone for all your help.

[mattison]

If you switched it from heat to a/c and the fan still did not come on then I would think you are having problems with the fan motor or cap. Look at the contactor in the outdoor unit with the power off and see if it is powered straight off of it or not.

[Grady]

But I don't understand what the outdoor fan has to do with the temperature of the air coming out of the vents. Can you post a pic or copy of the wiring diagram?

[mattison]

In heating mode without the outdoor fan the suction pressure would drop and in turn the head would drop causing lower discharge air temps at the vents.

[r-mallis]

i am not quit sure what the contactor is? anyways i called my home warranty company last night and they're going to send someone to look at it. the main thing i wanted to make sure of is that i really had a problem. i didnt want those guys to come out and say theirs nothing wrong with your heat and then charge me for a service call. the last time my buddy (who works for a heating and air company) came out i could not get it to act up, thats why he put a fan motor in it. anyways it happens every time i turn the heat on now so i dont think ill be wasting my money on a service call. thanks for all your help and i will post the results of my problem when i find out.

[r-mallis]

ok the repair guy just left and the problem was a bad fan relay on the defrost board. thanks again for all the input

[mattison]

Glad he found it. Stay warm or cool whatever mode you're in today.