Any HVAC pros??

[Gary H NC]

We have an older Carrier unit with the AC and gas pack.Model#48SS-024060321
I had the compressor serviced and its ice cold. 46* at the vents in the house.
The problem is the blower fan runs very slow.
I took everything apart,cleaned all the coils,replaced the seals between the return side and exhaust side of the fan compartment.That stopped a leak around the top of the outside unit that was blowing cold air outside.

I cleaned the cage fan.It turns very easy and the bearings in the motor feel smooth but it runs very slow.

The unit only cycles like it should at night when it cools the house off.

If i could get the fan speed higher i am sure the system would be fine.
Can barely feel it blow out the vents.

I went under the house in sealed all ductwork with mastic,all collars and joints are now sealed air tight.
I found one huge leak in the return side that is now fixed.

A new cage fan is 600 to 800 bucks!
Is there anyway to speed this one up? I don't think the fan motor is bad its just not running at full speed.
A neighbor AC guy said there is different connections on the circuit board for fan speed..
He never has time to come look at it..

 

[Gary H NC]

Re: Any HVAC pros??

BUMP.............

I did some research and found this unit has a 3 speed fan,220 volt.
It only runs on one speed. Checked with the meter and the fan is only getting 110 volts...

 

[Bass Man Bruce]

Re: Any HVAC pros??

I'm sorry I can't really help you Gary, but my impression on these is that they do have variable speeds so that they can service different sized houses.
You may have to call a pro.
Good luck

 

[stevenj]

Re: Any HVAC pros??

http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/48ss-4pd.pdf

Page 21 is a diagram for your unit you need to interchange the red wire from terminal BM and tape off and connect the black wire from the motor to the
BM terminal RED IS LOW SPEED,BLACK IS HIGH

BE CAREFUL TURN OFF POWER FIRST!!!!!!!!!!

 

[Gary H NC]

Re: Any HVAC pros??

Thanks stevenj.

They had the blue wire to the BM connection on the board.
I hooked the black wire to it.No notice of any faster speed.

There is also a red fan wire that is spliced with a wire nut to a black wire that connects to a terminal next to the circuit board on the right side.This has power, 120 volts at that connection checked it with the meter.
Someone has done some wire splicing before on it..

I need to post a pic if anyone knows this particular board...

 

[thefairlaneman]

Re: Any HVAC pros??

Ive had to do a repair on my trane but my guess is if it was running fine and now its slow there is what I call a starter(actuator) that runs from the motor to the hot wires that could be blown. Anyway why buy a complete cage when you would only need a motor, YOu shouldnt have to buy it from the maker , go to D and L located in charlotte on freedom drive and take the old motor with you for a perfect and much cheaper match. Its what I did . Seems like all of the service companys just want to sell you a new one so they OVER quote the repair cost. When it was serviced they didnt check the fan speed then?

 

[Gary H NC]

Re: Any HVAC pros??

Thanks Fairlane,

Trying to get the guy back out to look at it.
The fan runs so smooth i think its ok.
I believe its wired wrong or something on the circuit board is bad.
There are 2 resistors that look like they got hot at one time..

If i could ever get the AC guy down the road to come back out he would know.At least tell me what is bad and i'll find the parts...

Its blowing 46 degree air at the vents but its so weak as far as flow it does not keep up with the house.

 

[SS MAYFLOAT]

Re: Any HVAC pros??

You should have 220 on L2 and BM of the board. If not, something wrong on the board. At least that is what I would suspect according to the wiring diagram. BTW. make sure you do have 220 coming in for your supply voltage.

 

[Rickairmedic]

Re: Any HVAC pros??

Gary I are an HVAC pro . I would like a picture of the fan motor showing the wires comming fom the motor and the mounts for the motor if its a standard mount 48 frame motor you can get them for less than $100.00 your buddy down the street should have one on his truck . With the picture of the wires on the side of the motor and also if possible a picture of the wires on the board I can tell you how to wire it up . The black wire comming from the fan will be high speed and would go to BM the yellow wire from the fan motor should go to L2 if this doesnt increase your speed then you most likely have a bad motor but as was said you dont have to change the whole squirrel cage just the motor and capacitor.


Rick

 

[mike243]

Re: Any HVAC pros??

i would have the run capcitor cked,i have changed more in the last 2 years than i did in the 20 before,also pull the evap cover off,on the evap coil make sure the side coming from your indoor return is not stopped up ,if you measure the temp going into the return & the temp on the supply grills you should have 18-21 degree diffrence to cold can be stopped up evap coil,to warm low freon charge or dirty condenser coil,im wondering it if only has a 110v evap motor ? most 220v will not run with only 110 on it,mike243

 

[Gary H NC]

Re: Any HVAC pros??

Thanks guys...i'll get some pics of the board and fan after the rain stops.

The voltage at the BM connection is 120 volts...I checked the main power coming in and it was 220..

The whole unit was taken apart,all coils cleaned and the fan was cleaned.
The fan has run slow for a couple years now.

Will post some pics later today.Thanks for all the help!!

 

[stevenj]

Re: Any HVAC pros??

You need to put your meter leads between BM and L2, tell us what that voltage is.I assume you are putting meter leads on BM and ground. This will
show only 120.

 

[Gary H NC]

Re: Any HVAC pros??

You need to put your meter leads between BM and L2, tell us what that voltage is.I assume you are putting meter leads on BM and ground. This will
show only 120.

You were correct...no wonder it was showing 120 volts....duh!

Hooking the meter to BM and the other main power lead gives me 240 volts.
Did not try BM and L2 together yet.
Just snapped some pics..gotta get them on photobucket...

 

[Gary H NC]

Re: Any HVAC pros??

double post.....argh! Deleted..

 

[Gary H NC]

Re: Any HVAC pros??

OK...BM to L2 is 240 volts...

Here are some pics....i noticed 2 resistors that are side by side are kind of burnt looking around them on the circuit board..


Here is the best pics i could get...Yellow from fan is on L2....Black to BM
No difference in speed when hooking blue to BM.

 

[Gary H NC]

Re: Any HVAC pros??

Under the fan...

one more of the board,

 

[Rickairmedic]

Re: Any HVAC pros??

Gary somebody has done something funky in there at some point from the pics it looks like the red ( low speed blower lead ) is wirenutted to a black wire that is going over to the contactor . That should not be there and may be why you are only running in low speed . I want you to try something for me pull the disconnect out and unhook that wire from the contactor . Then plug the disconnect back in and see what the fan motor does. Let me know I will be around here tonight if you need to PM me a phone number and I will call you .


Rick

 

[Gary H NC]

Re: Any HVAC pros??

I did unhook the red wire from the wire nut yesterday and it made no change.

So you are saying to just remove the black wire from where it connects at the contacter?

 

[Rickairmedic]

Re: Any HVAC pros??

Gary yes thats what I am saying is to remove the black/red wire from the contactor it shouldnt even be there as thats the lowspeed wire for the motor.

Rick

 

[Gary H NC]

Re: Any HVAC pros??

Will do...going out the door now to do it now.
I'll post back.

Thanks SO MUCH for the help!