Need Some HVAC Help Please - HVAC - DIY Chatroom Home Improvement Forum


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

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

Reply
 
Thread Tools Display Modes
Old 04-04-2011, 05:23 PM   #1
Newbie
 
Join Date: Apr 2011
Posts: 3
Rewards Points: 10
Default

Need Some HVAC Help Please


Got a question about a 2.5 ton 14 seer goodman condensing unit. Condensing unit will not run (fan or compressor). i have checked for power at the contactor. Everything is live including the low voltage. We noticed the unit has built in pressure switches on the low and high side. We have bypassed both of them to try and force the compressor to start. WE NEED HELP PLEASE!!!

Advertisement

handydamn is offline   Reply With Quote
Old 04-04-2011, 05:50 PM   #2
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 1,000
Default

Need Some HVAC Help Please


If you have 24 volts at the contactor but it's not pulling in then the contactor is bad.

If the contacor is pulled in and has 240v going through it then the capacitor is likely bad.

Advertisement


Last edited by Marty S.; 04-04-2011 at 05:54 PM.
Marty S. is offline   Reply With Quote
Old 04-04-2011, 05:56 PM   #3
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,040
Rewards Points: 718
Default

Need Some HVAC Help Please


Make sure you are checking for 24 volts ON the 2 terminals of the contactor and NOT to ground.
__________________
"Cut it twice and it is still too short".
yuri is online now   Reply With Quote
Old 04-04-2011, 11:02 PM   #4
Newbie
 
Join Date: Apr 2011
Posts: 3
Rewards Points: 10
Default

Need Some HVAC Help Please


The contact switch and the capacitor were both replaced. This is a brand new unit. We just installed it yesterday. The contact switch opens and closes just fin and there is 120v at all 4 sides. This one is mind boggling. All wiring has been double checked. What could could cause a brand new unit not to run at all. (Fan and compressor) there is no reset button like on heat pumps. We are stumped.
handydamn is offline   Reply With Quote
Old 04-04-2011, 11:43 PM   #5
I'm Your Huckleberry
 
Join Date: Mar 2011
Posts: 5,884
Rewards Points: 2,220
Default

Need Some HVAC Help Please


Quote:
Originally Posted by handydamn View Post
The contact switch and the capacitor were both replaced. This is a brand new unit. We just installed it yesterday. The contact switch opens and closes just fin and there is 120v at all 4 sides. This one is mind boggling. All wiring has been double checked. What could could cause a brand new unit not to run at all. (Fan and compressor) there is no reset button like on heat pumps. We are stumped.

Either low (not enough refrigerant, most likely the case as you possibly have a refrigerant leak) or high PRESSURE limit switch is tripped.

Freon levels need to be checked but alas, the unit needs to be running for that although if you have refrigerant gauges you can connect them to the high and low side ports and if the gauges read extremely low to nothing with your system off, there's your problem.

Check for oil at the copper line connections where the new unit was brazed in.
Doc Holliday is offline   Reply With Quote
Old 04-04-2011, 11:43 PM   #6
Experienced
 
Jackofall1's Avatar
 
Join Date: Dec 2010
Location: Southern Michigan
Posts: 2,822
Rewards Points: 2,000
Default

Need Some HVAC Help Please


Quote:
Originally Posted by handydamn View Post
The contact switch and the capacitor were both replaced. This is a brand new unit. We just installed it yesterday. The contact switch opens and closes just fin and there is 120v at all 4 sides. This one is mind boggling. All wiring has been double checked. What could could cause a brand new unit not to run at all. (Fan and compressor) there is no reset button like on heat pumps. We are stumped.
Just a question, 120 V on all 4 sides? Shouldn't that be 240 V?
__________________
When its all said and done there is usually more said than done
Jackofall1 is offline   Reply With Quote
Old 04-04-2011, 11:56 PM   #7
I'm Your Huckleberry
 
Join Date: Mar 2011
Posts: 5,884
Rewards Points: 2,220
Default

Need Some HVAC Help Please


A low (refrigerant) pressure switch that has been tripped will not allow the entire unit to come on (btw, a condenser fan will not run unless the compressor is running) UNTIL refrigerant is added. If the system is off so you can hear, as refrigerant is added you will hear a "click" which will be the switch closing thus allowing the call for the entire unit to come on. Since the unit will not run and if indeed it is due to the low pressure switch tripping, due to lack of freon, the only way to add refrigerant is with the unit off (through the high side in liquid form) so you will be able to hear the switch closing. Once the switch is closed the unit will start and the system then can be properly charged to normal operating range.

The only thing electrical about this is that the low refrigerant pressure switch is internally cutting (opening) the circuit that is calling for the unit to come on, thus saving your brand new compressor.

Good luck and please let us know what the problem was.

.
Doc Holliday is offline   Reply With Quote
Old 04-05-2011, 07:40 AM   #8
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 1,000
Default

Need Some HVAC Help Please


Quote:
Originally Posted by Jackofall1 View Post
Just a question, 120 V on all 4 sides? Shouldn't that be 240 V?
Good call. Checking each leg to ground with the contactor pulled in would give 120V even if there's one leg powered. Put the meter leads on L1 and L2 at the same time and then on T1 and T2 at the same time. Bet you're missing a leg of power. Fuses in the disconnect?

Pressure switches are before the contactor in the low voltage circuit so it wouldn't pull in if there was a problem with the charge.
Marty S. is offline   Reply With Quote
Old 04-05-2011, 07:42 AM   #9
Member
 
Join Date: Mar 2010
Location: PENNSYLVANIA
Posts: 2,258
Rewards Points: 1,044
Default

Need Some HVAC Help Please


Quote:
Originally Posted by Marty S. View Post
If you have 24 volts at the contactor but it's not pulling in then the contactor is bad.

If the contacor is pulled in and has 240v going through it then the capacitor is likely bad.
" Short and sweet and right" Listen to Marty.
COLDIRON is online now   Reply With Quote
Old 04-05-2011, 09:28 AM   #10
I'm Your Huckleberry
 
Join Date: Mar 2011
Posts: 5,884
Rewards Points: 2,220
Default

Need Some HVAC Help Please


Quote:
Originally Posted by handydamn View Post
Got a question about a 2.5 ton 14 seer goodman condensing unit. Condensing unit will not run (fan or compressor). i have checked for power at the contactor. Everything is live including the low voltage. We noticed the unit has built in pressure switches on the low and high side. We have bypassed both of them to try and force the compressor to start. WE NEED HELP PLEASE!!!

Needless to say I completely missed that. Put them back.
Doc Holliday is offline   Reply With Quote
Old 04-05-2011, 11:21 AM   #11
Newbie
 
Join Date: Apr 2011
Posts: 3
Rewards Points: 10
Default

Need Some HVAC Help Please


We got it now. It was the breaker in the main power box in the house. I did not know that each side of the contact switch needed to be at 220v i thought each side needed to be 120V and the 2 sides would be equal to 240v. replaced the braeker and it works fine now. Thanks for all the help
handydamn is offline   Reply With Quote
Old 04-05-2011, 11:23 AM   #12
Experienced
 
Jackofall1's Avatar
 
Join Date: Dec 2010
Location: Southern Michigan
Posts: 2,822
Rewards Points: 2,000
Default

Need Some HVAC Help Please


Quote:
Originally Posted by handydamn View Post
We got it now. It was the breaker in the main power box in the house. I did not know that each side of the contact switch needed to be at 220v i thought each side needed to be 120V and the 2 sides would be equal to 240v. replaced the braeker and it works fine now. Thanks for all the help
Thanks for posting back, glad to hear it was a simple fix, 9 out of 10 times they are.

Mark

Advertisement

__________________
When its all said and done there is usually more said than done
Jackofall1 is offline   Reply With Quote
Reply


Thread Tools
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
Runaround - HVAC and HWH proper venting/exhaust denemante HVAC 24 04-05-2011 09:50 PM
moving HVAC system - can I go without gas for a few days? denemante HVAC 2 03-30-2011 05:55 AM
History of HVAC Industry Brands winkydink HVAC 8 03-25-2011 08:28 AM
Moving HVAC system dilemma denemante HVAC 4 03-18-2011 05:55 PM
Engineered Joists & holes for HVAC ducts walt1122 Building & Construction 3 07-04-2009 08:37 PM




Top of Page | View New Posts