carrier info/help

[vzenuh]

The unit is working fine right now but let me give a lil info.
Carrier 50hjq006-507

I arrive and the unit is off. I remove covers and find that there is a call for cooling at the terminal of the rtu but the contactor isn't pulled in. I push the contactor and it grabs and the unit fires up. HMMMMMMM. I kill power to the unit, wait a minute and restore power to it and wait for the delay.

I check for voltage at the contactor and I am only getting 6 volts. I again push in the contactor and it holds and the unit fires up. I recheck voltage again and now it's 25 volts.

Now I start checkin every safety in line with the contactor. they all spec out. I go to the compressor lockout board and find that I have 25 volts in and only 6 out.

Make I long story short,, I replaced the board and everything is fine.

Question is,,,, I believe from two to three it is a normally closed switch, only the current sensing part of the board can open the switch. With no current the switch should be closed. And why when I push in the contactor does the board pass power as it should.

I understand that sometimes electrical things act funny,,, but I would like a more direct answer to this quesiton.

Yes I did check amps and everythign that goes with that,,, what I need to know,,, is what can cause this problem,,,, weak relay in the board, something faulty, bad connection, I am sure someone out there has had the same problem and has a perfect theory on what happens.

[VTP99]

Do a Thread search. You should find your answer. ;)

[rundawg]

Carrier 50hjq006-507

Question is,,,, I believe from two to three it is a normally closed switch, only the current sensing part of the board can open the switch. With no current the switch should be closed.

I would like a more direct answer to this question.

COMPRESSOR LOCKOUT RELAY(CLO):

If compressor operation is interrupted by an open high-pressure switch, low-pressure switch, indoor coil freezestat, or by compressor internal line-break device (over current or over temperature), and compressor is calling for either cooling or heating, CLO protection device simultaneously locks out the unit by opening the normally closed contacts between 2 and 3, and lights a warning light on the thermostat by closing the normally open contacts between 2 and X.

To restart the unit, manually turn the thermostat to OFF, and then to the ON position. If any of the protective devices opens again, the unit continues to lock out until corrective action is taken.

If the unit fails to operate due to compressor over current condition, you must restart by manually resetting circuit breakers at the unit. Restart cannot be accomplished at the room thermostat.

I'm not sure exactly what the CLO needs to see for amps draw, but I have read it needs to see at least 1.5 amps, or it will open contacts 2-3 and close 2-X. Don't quote me on this.

[skippedover]

I'm totally out of my element on the specifics of the control circuit to which you refer but in basic electrical circuits, the pick-up volts/amps must be sufficient to close the contactor. Once closed, a much lower holding volts/amps can keep the contactor closed. I believe that by manually pushing in the contactor, you've eliminated the higher volts/amps needed to close the contactor but once closed whatever volts/amps are needed for holding it closed were present and therefore kept it closed. Just like pushing a car. It takes a lot more energy to get it moving than it does to keep it moving.