HVAC guys are cool............get it???

eman1200

eman1200

Touchdown! Greaser!
Joined
Mar 10, 2013
Messages
21,718
Location
Oakland, CA
Display Name
Bro do you even lift
I need to replace a capacitor in my HVAC unit in the attic. below are the #'s off the current one, I'm having a hard time finding an exact replacement part:

Hq1094239Ax 0246-5 MRP137034 70 C 7.5uf 370vac 50/60Hz PO C 40/70/21 c22 2 No 190 M22P3707N00 SUPERNOL

and it's round, not oval, if that matters. cause a lot of the ones I'm seeing are oval but I still can't match up the specs.

thanks!
 
Whoops, sorry, misread it was round.

Ignore this part:
You mean this one: https://www.amazon.com/TEMCo-Motor-Capacitor-RC0049-7-5-Electric/dp/B01A4C55L2 ?
Or this one: https://www.amazon.com/Genteq-GENTE...8VELRGI/ref=pd_lpo_1?pd_rd_i=B008VELRGI&psc=1

Round:
Maybe this one: https://www.amazon.com/Run-Capacitor-7-5-Mfd-370-450V/dp/B01FT2YVSA

Or go search "mouser.com" for "CAP-7.5/440R" but I can't find the dimensions for it.


This part is still useful:
Most important: 7.5uf
Minimum: 370VAC and 70C.
So, 440VAC and 85C would be fine.

The other more important part is the actual dimensions.
 
Last edited:
chartbundle said:
Whoops, sorry, misread it was round.

Ignore this part:
You mean this one: https://www.amazon.com/TEMCo-Motor-Capacitor-RC0049-7-5-Electric/dp/B01A4C55L2 ?
Or this one: https://www.amazon.com/Genteq-GENTE...8VELRGI/ref=pd_lpo_1?pd_rd_i=B008VELRGI&psc=1

Round:
Maybe this one: https://www.amazon.com/Run-Capacitor-7-5-Mfd-370-450V/dp/B01FT2YVSA

This part is still useful:
Most important: 7.5uf
Minimum: 370VAC and 70C.
So, 440VAC and 85C would be fine.

The other more important part is the actual dimensions.
Click to expand...

Yeah, mine is round with a round mounting bracket. Guess I could bend up a new one, but also the connectors look different and with no markings on them….

7fc29dc962bfe29d35234c8035fe758f.jpg

4706bd34016737b79f20f3b3d8f4963d.jpg

46b8939bbc3b15a9d86d4e66a2981aae.jpg

d3cdfcfa7c05b355239c3a116ccb4292.jpg
 
eman1200 said:
I need to replace a capacitor in my HVAC unit in the attic. below are the #'s off the current one, I'm having a hard time finding an exact replacement part:

Hq1094239Ax 0246-5 MRP137034 70 C 7.5uf 370vac 50/60Hz PO C 40/70/21 c22 2 No 190 M22P3707N00 SUPERNOL

and it's round, not oval, if that matters. cause a lot of the ones I'm seeing are oval but I still can't match up the specs.

thanks!
Click to expand...
And HVAC gals are hot. Are you sure you don't wanna call for some help?

images
 
Might want to view a youtube on how to remove the charge from your current one prior to removal.
 
Yes, there will be no markings. It's an AC capacitor, it doesn't care which way around, in your case one wire to one side, one wire to the other.
(Note, this only applies to this type of capacitor not the start+run below.)

Checkout_my_Six said:
this one should work.....
https://www.amazon.com/PowerWell-Ca...ocphy=9008021&hvtargid=pla-572008906078&psc=1
Click to expand...
This is a combined start+run capacitor which is probably not what you want, but if you choose the right connections you could make it work if you can't find anything else. (May also be dual for condenser+fan, either way it's not quite right)
 
I understand that the 7.5uf or 7.5mfd and 370v is important, what I don't understand is the rest of the #s and what they mean. imma try the round one chart suggested, tyvm!
 
I'm not sure if this is the problem or not, but if I hit the switch in the video the motor will turn on for about 5 seconds then shut off. fan is not coming on by using the thermostat, and the line on the outside fan unit is freezing up. I've changed all the filters in the ceilings, I cannot locate a single filter anywhere on the HVAC unit in the attic whatsoever, and I figure the capacitor is a cheap enough part to replace, I might as well try that first:

https://youtube.com/shorts/Im0hys_4AsA?feature=share
 
FORANE said:
Might want to view a youtube on how to remove the charge from your current one prior to removal.
Click to expand...

Where's the fun in that? Everyone deserves one naive encounter with a capacitor before they learn to approach them with more caution.

Although the capacitor in the pic looks like a big 'un.
 
GaryM said:
Where's the fun in that? Everyone deserves one naive encounter with a capacitor before they learn to approach them with more caution.

Although the capacitor in the pic looks like a big 'un.
Click to expand...

I think my dog is gonna have a new toy to play with!
 
We just replaced the complete HVAC system on Friday, hats off to the crew who spend at least 6 hours workin the attic on a 101 degree day in Phoenix…
 
For component capacitors, I'd go to mouser or digikey. But for a motor capacitor, wired up in a metal enclosure with quick connect tabs on it, I'd go to an electrical supplier. Mcmaster isn't one of those, but they still carry those:

https://www.mcmaster.com/motor-run-capacitors/

You want the capacitance to be roughly the same (7.5uF), and the AC voltage equal or greater. The rest doesn't matter. The capacitor specs for those things is probably +100/-20% or something, and they degrade with time, so I'd just get one that has a high enough AC voltage and fits mechanically.

That's not a lot of charge, like 100 times less than a photo flash cap, but you can still discharge it with a screwdriver if you want. No idea if a 7uF capacitor would cause much of a shock. 450uF at 400V? Yep. BTDT.
 
If the fan isn't running the pressures will get too high and stall the compressor, tripping it out. Best way to determine if it's the capacitor is to test it. Most likely it's the capacitor, contactor or fan motor. A good volt/ ohm meter with a conpacitance test function makes diagnosing pretty easy.

If it's a super efficient model with variable speed motors, then it might be a little tougher to figure out.
 
PaulS said:
If the fan isn't running the pressures will get too high and stall the compressor, tripping it out. Best way to determine if it's the capacitor is to test it. Most likely it's the capacitor, contactor or fan motor. A good volt/ ohm meter with a conpacitance test function makes diagnosing pretty easy.

If it's a super efficient model with variable speed motors, then it might be a little tougher to figure out.
Click to expand...
On my super efficient model with variable speed motors it has a board that will throw a code indicating the capacitor has failed, making it pretty easy. Thats kind of like the obd on a car...
 
Albany Tom said:
…You want the capacitance to be roughly the same (7.5uF), and the AC voltage equal or greater. The rest doesn't matter. The capacitor specs for those things is probably +100/-20% or something, and they degrade with time, so I'd just get one that has a high enough AC voltage and fits mechanically...
Click to expand...

Very helpful, thanks. Also why I was having a hard time finding a good match, I was trying to get all the #s to line up.



PaulS said:
….If it's a super efficient model with variable speed motors, then it might be a little tougher to figure out.
Click to expand...

It is neither of those. Probably the most el cheapo model around.
 
If you have everything set to be working and hold the switch in, can you give the fan a spin manually and see if it starts? The capacitor is, typically, nothing more than a start capacity to give it a kick to start it. No??

And that switch looks like a cover switch so the system won't turn turn on with the cover off. Are you having an inside unit blower motor issue or outside unit fan issue?

I just had a blower motor go south on a property and it would kick on for a bit then shut the whole system down. The blower motor had a built in circuit board as well so the stupid thing cost $800! This one was on a package unit so everything is in a box outside with nothing but duct work in the house.
 
simtech said:
If you have everything set to be working and hold the switch in, can you give the fan a spin manually and see if it starts? The capacitor is, typically, nothing more than a start capacity to give it a kick to start it. No??

And that switch looks like a cover switch so the system won't turn turn on with the cover off. Are you having an inside unit blower motor issue or outside unit fan issue?

I just had a blower motor go south on a property and it would kick on for a bit then shut the whole system down. The blower motor had a built in circuit board as well so the stupid thing cost $800! This one was on a package unit so everything is in a box outside with nothing but duct work in the house.
Click to expand...

basically I turned the AC on for the first time then went out back to smoke a stogie. I noticed the fan outside was running and running and didn't stop for a looong time, and that's unusual. so I looked at it and blamo, the main pipe to the outside unit was frozen solid, iced up all around. the fan on the hvac unit in the attic never went on...OR, it spun for a few seconds then stopped, like in the video. a few years ago I had a guy come out to take a look and he tested the capacitor and said it was pretty low and I was like meh, I'll wait to change it, but again that was several years ago. from my research, most people are saying it's probably a clogged up HVAC filter but there is literally no filter anywhere on that unit that I can see. I have filters (3) in the ceilings that I change every quarter, and I changed them again yesterday but they were fine as is. only other thing I know I can do is change that capacitor. if that doesn't fix it, I'm at a loss because I know nothing about these HVAC units and I'll prob have to call someone to rip me off take a look.
 
Does the inside fan hum while it's supposed to be on? I'm with you, capacitor or blower motor. But I still feel if the capacitor you could give the motor a fling and it should start.
 
simtech said:
Does the inside fan hum while it's supposed to be on? I'm with you, capacitor or blower motor. But I still feel if the capacitor you could give the motor a fling and it should start.
Click to expand...

good question......so what normally happens when the ac is about to kick on is I'll hear 'something' going on with the hvac unit in the attic....not really sure what's going on, just an initial "I'm getting ready to start doing something" kind of noise......then the main fan kicks on and blows cool air. so I'm thinking the initial sound I hear is that thing that kicks on when I hit that cover switch you were talking about, then maybe the main fan goes on? I really don't know lol. but now what's happening is I'll hear that initial 'getting ready to go' sound then it just stops and no main fan goes on and nothing happens. the hvac unit inside is a horizontal one, with 'the thing that spins around' from the video on the right, and I'm guessing the main fan on the left? IF it's that main fan, I wonder if that's easily replaceable. I replaced the fan and capacitor on the OUTSIDE unit a few years ago that was pretty easy, other than waiting for the fan unit to come in which took 4 days during a nice 90+ degree streak.
 
cd4820f250f7672ecf8cb8d24b48de24.jpg

de64548ee1b38488aa56c594441e6e5c.jpg


Top pic: Main fan thingie with capacitor on the left side of the unit

Bottom pic: “black thing that spins” after hitting the cover switch several times.
 
Ah I was just gonna ask if it's a gas unit and it is. That sound you spoke of, the initial sound before the main fan sounded like the exhaust fan that starts up for a gas furnace. What does that mean...I don't know hahaha. Just observing.
 
Have you killed the main breaker for the unit for a minute of two? I had that same issue with a furnace and the inside unit. That circuit board looks the same I had, it was hanging up on some sensor that reset with the power off.

Is there a green LED on that board that flashes when it fails? Could be giving a code and those are usually on the inside cover.
 
simtech said:
Have you killed the main breaker for the unit for a minute of two? I had that same issue with a furnace and the inside unit. That circuit board looks the same I had, it was hanging up on some sensor that reset with the power off.
Click to expand...

are you basically asking me "have you rebooted?" lol yes, I cycled the main breaker once but didn't leave it off for a bit. I can do that now, just for funsies.
 
Hahaha yep reboot. I might have edited my post after you responded but any green LED light on that circuit card?
 
simtech said:
Hahaha yep reboot. I might have edited my post after you responded but any green LED light on that circuit card?
Click to expand...

I don’t recall seeing any light but I wasn’t looking for one.

62e9e17cc5fa9f7d7b80006925a50d51.jpg


The capacitor is supposed to be delivered today so I’ll swap that and try again and also look for a light, but in the pic I don’t see one anywhere.
 
Turn it on, spin the fan by hand. If it starts up its the cap, if not you need to dig deeper.


BTW, cheaper is better, at least where I am, in NH.
 
I doubt it’s the cap. See that little orange tubing coming off your “black thing that spins”? That’s for the gas valve pressure switch. Once the small fan starts turning it will (I forgot- it’s been a looooong time) pull a slight vacuum or build a slight pressure in the tube to trigger the pressure switch. Try finding the other end of the orange tube, make sure it’s connected. If it is, unhook it at the “spin”nd and try to start the unit again, this time with the end of that tubing in your mouth, pulling a very slight vacuum (or pressure) while trying to get it to start. Gently. Tiny amounts of pressure/vac. Like an asi. Don’t ruin the switch, in case it’s not the problem.
 
eman1200 said:
hhhmmmm, should I do that while grabbing both terminals on the capacitor? :rollercoaster:
Click to expand...

It won’t help. (Your capacitor is fine.) It’s a piece of rubber tubing that triggers the pressure switch after your “black thing that spins” pulls a slight vacuum. Try it. Put a drinking straw in the end of the orange tubing if it helps make it long enough to be able to draw on it while you hit the go button.

Or, wuss out and don’t try my advice, call someone, spend $$$ fir them to do that exact thing I described. ;)
 
You must log in or register to reply here.
Back
Top