walk in freezer not going into defrost

[royd2]

what would cause my compressor to keep runing while in defrost , this is a pumpdown system. changed time clock twice still same problem

[mattt787]

did you have your gages on the system if it was pumping down you would see the low side drop and the high side would go i know this might be basit but if that does not happen the liquid line secanord might not be closing

[royd2]

thanks ar. i am posting this after the fact as i tried to tell the senior tech to check solonoid and pressure cut out. i quess what i am asking is if my compressor never shuts off my time clock will never allow my defrost heaters to come on correct?

[ar_hvac_man]

thanks ar. i am posting this after the fact as i tried to tell the senior tech to check solonoid and pressure cut out. i quess what i am asking is if my compressor never shuts off my time clock will never allow my defrost heaters to come on correct?

Compressor shutdown doesnt initiate defrost, your clock does. Your compressor could continue to run while your heaters are energized.

[jpsmith1cm]

Compressor shutdown doesnt initiate defrost, your clock does. Your compressor could continue to run while your heaters are energized.

This is not necessarily true.

Many times, the electrical circuit to the condensing unit is only large enough to run the compressor OR the heaters, but not both.

Thus, there is often an interlock so that the compressor must cycle off before the defrost heater contactor can energize.

[steve36558]

Well on some larger systems the heater won't energize till compressor shuts off. Heater relay off aux contacts on compressor contactor. Your post #13 is a good starting point to check.

[ar_hvac_man]

I agree. I dont see them often but there are systems set up and wired that way. No offense to the OP but hes obviously lost(we all were at some point) so I posted what I felt he needed to tackle first.

[supertek65]

defrost timer de-energizes ll solenoid valve and then compressor will run until pressure switch opens.

[royd2]

ok thats what i thought so we need to check our elements and solonoid and pressure cut out then.

[royd2]

could a bad defrost termination switch also cause my heaters to not come on ?

[royd2]

idk somehow reading hotter temp than actual

[royd2]

ok thanks thats what we will try

[royd2]

i will post back tomorrow, thanks again