Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 06-30-2013, 04:32 PM   #1
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 456
Rewards Points: 302
Default

Not sure about these compressor ohm readings


Packaged A/C-only unit, Carrier - 23 years old, for a single-wide mobile home.

Compressor is pulling 11.5 A. Can't read data plate on outside of cabinet for compressor spec. Blower motor is pulling about 2.5A - data plate on this motor: 2.7 A, but blower motor will not start on its own, but will with a push. Blower motor capacitor spec (on cap) is 370vac/7.5 uF. This cap measures 7.02 uF.

When I opened up this unit, evap. coil was iced up. Cleaned coil - still ices up after I give blower motor a push and let it run. Motor is getting 240v. I also hear a bearing noise after blower motor speed has slowed down quite a bit (after system being turned off). Correct me if I'm wrong, but blower motor appears to need replacement*. As I mentioned, blower motor is getting 240v when measured at cap common terminal and relay terminal. *unless wires feeding the blower motor are bad, but judging by their wire ends at capacitor and relay, looked fine to me.

I installed new contactor and dual run capacitor: 35/5 uf, 370vac. Also went thru all wiring connections - cleaned all quick disconnects or made new ones, including connections at compressor (cleaned only - didn't need new ones here). Comp. terminals were in very good condition.

I figured the icing up was due to low R-22, but don't have guages yet.

Ohms check was S-C: 2.2; R-C: .8; S-R: 2.5 . Acceptable?

justplumducky is offline   Reply With Quote
Old 06-30-2013, 05:08 PM   #2
Member
 
Join Date: Mar 2007
Location: Eighty Four, Pa.15330
Posts: 1,282
Rewards Points: 562
Default

Not sure about these compressor ohm readings


To me no. Readings should add up evenly. Like 5 ohm+ 5 ohm,=10 ohm.


Last edited by bobelectric; 06-30-2013 at 05:13 PM.
bobelectric is offline   Reply With Quote
Old 06-30-2013, 05:18 PM   #3
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 25,518
Rewards Points: 2,716
Default

Not sure about these compressor ohm readings


May have a shunt in windings. I prefer to test the cap under load on cases where the motor runs, but doesn't run properly.

Testing by meter can give a false reading of it being good.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
Old 06-30-2013, 05:54 PM   #4
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 456
Rewards Points: 302
Default

Not sure about these compressor ohm readings


Quote:
May have a shunt in windings.
You were talking about the compressor ohms readings here, and saying my comp. readings could be ok?
Quote:
Quote:
Quote:
I prefer to test the cap under load on cases where the motor runs, but doesn't run properly.
How do you do that?
justplumducky is offline   Reply With Quote
Old 06-30-2013, 06:02 PM   #5
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 25,518
Rewards Points: 2,716
Default

Not sure about these compressor ohm readings


Quote:
Originally Posted by justplumducky View Post
You were talking about the compressor ohms readings here, and saying my comp. readings could be ok?
How do you do that?
I thought you took the ohm readings of the fan motor.

2652 times the amp reading of the start winding, divided by the voltage reading across the capacitor.

EG: .9 amps, 332 volts across cap.

2652 times .9 equals 2386.8
2386.8 divided by 332 equals 7.18 uF.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
Old 06-30-2013, 06:48 PM   #6
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 456
Rewards Points: 302
Default

Not sure about these compressor ohm readings


Yepper - sorry - I started to explain (then didn't) that I may have muddied the waters (the way I posted all that) by not explaining that it was the compressor ohm readings at the bottom.

Quote:
Originally Posted by beenthere View Post

2652 times the amp reading of the start winding, divided by the voltage reading across the capacitor.

EG: .9 amps, 332 volts across cap.

2652 times .9 equals 2386.8
2386.8 divided by 332 equals 7.18 uF.
Ok, you're saying that is the calculated, actual uF output of the cap vs. a possible erroneous meter reading.

Whaddya make of those compressor ohms readings: S-C: 2.2; R-C: .8; S-R: 2.5 - Acceptable? Close enough? Just never saw readings before where the S-R totaled less than the other two, so was wondering. But then I've only done a relative few.

Comp. was pulling 11.5 A. Couldn't read the cabinet's data plate for the comp. amps spec., but guessed that might be in the neighborhood, especially if R-22 were a bit low.
justplumducky is offline   Reply With Quote
Old 06-30-2013, 06:55 PM   #7
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 25,518
Rewards Points: 2,716
Default

Not sure about these compressor ohm readings


May have some minor oil break down/losing its dialectic properties. Or he winding insulation is getting thin. Nothing that is too terrible.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
Old 06-30-2013, 07:10 PM   #8
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 456
Rewards Points: 302
Default

Not sure about these compressor ohm readings


Thank you beenthere - have a good night!
justplumducky is offline   Reply With Quote
Old 07-01-2013, 10:52 AM   #9
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 456
Rewards Points: 302
Default

Not sure about these compressor ohm readings


Went back to this blower motor that wouldn't start without a push and installed new 7.5 uf, 370vac cap on the two brown wires (multi-speed motor), and nothing - not even trying to move the wheel. 240vac at motor's white lead on cap "C" and fan relay (black wire from motor).

I did an ohms check between the two brown wires (one with white stripe) from motor to single capacitor: bouncing around between 3 MegOhms and 12 MegOhms (occasionally up to OL), but after watching a youtube video, the correct way to ohms check the start winding is from black to solid brown wire?

Last edited by justplumducky; 07-01-2013 at 01:21 PM.
justplumducky is offline   Reply With Quote
Old 07-01-2013, 03:55 PM   #10
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 25,518
Rewards Points: 2,716
Default

Not sure about these compressor ohm readings


Yes..

__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Correct voltage readings on a 120v circ. stress78 Electrical 3 04-06-2011 01:56 PM
water heater relief valve dripping (with gauge readings) ziguan Plumbing 10 01-28-2011 10:12 AM
HVAC Compress Guage Readings? djwb HVAC 37 09-11-2010 03:26 AM
How do I know if my ohm readings on fan and compressor mean good? webejamin_1982 HVAC 5 11-21-2009 02:22 PM
need quick general advice on moisture readings Constant Improvement Flooring 2 12-24-2008 09:11 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.