TK won't shut down on cycle.

[TysonTech]

Hello,

I'm working on a 2002 Thermo King SB-300 trailer mounted unit. The problem is that while in cycle mode it won't shut down once it reaches temperature. It simply flips back and forth between heat/cool. I've checked the discharge air and return air sensors and they seem to be working properly. The maintenance manual I have suggests a "air short cycling around evaporator coil". I honestly don't know what that means. Looking for any ideas or an explination of what the manual was describing.

Thank you in advance.

[cadwaladr]

it could be several things ,alternator,water temperature sensor wiring?

[moggy66]

I agree with cadwaladr, water temp or alt , check all your setting one must be not reading correctly

[gravy258]

when its doing the heat/cool thing, what are the battery amps and volts ?
usually its the battery that will stop it cycling off

[giath]

hi
check cycle sentry relay.......good luck

[tkman]

Check amps, if it's over 5 amps it won't shut down.

[johnatr]

I have ran into the same problem and found that the amps on the micro were jumping all over the place. Thought might be a wiring problem, still working on it. Let me know what you find out if you don't mind.