KFIS29PBMS01 both FC and RC don't reach set temperature

[max999]

Hi, I have a KitchenAid Fridge model KFIS29PBMS01 and the FC/RC don't reach the set temperatures. 

RC reads 41.5F(with my Tc) and the resistance valves at the RC thermistor at P5 plug is 6.88Kohms (thermistor chart shows 41.5F for 6.88Kohms, so this is good)

FC reads 18.5F(with my Tc) and the resistance valves at the FC thermistor at P5 plug is 14.2Kohms (thermistor chart shows 16.5F for 14.2Kohms, so its off by 2F)

I also have the both FC evap and RC evap  covers put back and thermistor are in their correct position.  Compressor cover is also put back. 

my question is why is it that  RC or FC never reach the set temperatures of 33F and -5F i set in the fridge front panel display?

Thanks

Max.  

 

[16345Ed]

Can we assume no frost build up anywhere since you didn’t mention it? This would impede airflow. 
 

Could be a couple reasons, could be sealed system leak or restriction. Would be evidenced by uneven frost pattern on evaporator. 
 

Could be an evaporator fan not operating. 

[16345Ed]

I believe design also may have a manufacturer service bulletin published about frost up issues. 
 

You may want to hire a technician that has access to kitchen aid bulletins. 

[max999]

i did see uneven frost pattern on the FC evaporator.  Something else i discovered the this morning that after the fridge was power-up (@13:00 yesterday) and with the evap covers  back on the FC temp did dip down to -1F overnight,  but the following morning(6am)  I noticed that the low pressure deep to -20psi(vacuum) I touched the condenser and the cap lines and they were at room temp, with the compressor running/cond fan running,  the FC&RC Evap Fan  work. I then went into diag mode which turns off the compressor and noticed that the High/Low pressures equalize right away. if there was a restriction the pressure will NOT equalize , correct?  so what is it, is there a leak? 

[David C]

-20 could be an indication of a restriction. You could always give the system a bump of refrigerant and see what it does. What were the high side pressures?

[max999]

few minutes ago the compressor was off probably due to defrost , and now its back on and the pressure reads Low@18PSI , High@125PSI and the condeser/cap line are warmer then room temps. I just heard the compressor kick into higher speed and the pressures are dropping , low@1PSI and High@160PSI , FC/RC temp@38F/38F. 

[max999]

when you say "give the system a bump of refrigerant" , how much refrigerant are we talking about 1/2oz or less. ?

 

[max999]

now, an hour later, the pressure is 0PSI, and the FC/RC temps are 13F/39F , not sure what is going on. any idea? 

[max999]

more data points, FC temp continues to drop now at 9F, RC@39F, low pressure@0-1 PSI. could it be overcharged? 

[David C]

What is high side pressure?

[David C]

Could be a floating restriction. Your pressures are all over the map.

i would recover replace drier and purge with nitrogen and recharge, since you’ve tapped the system.

[max999]

here are the reading as of now: FC@16F, RC@39F, Low=@10PSI(Vacuum), High@125PSI, condenser and cap tube room temperatur.

[max999]

could you still have floating restriction with pressure always equalizing every-time the compressor is off.,? 

[max999]

also, is it worth it to still  "give the system a bump of refrigerant"

[max999]

is it possible the system is undercharged? since when a system is overcharge a frost will appear on the capillary lines by the compressor, correct? 

so maybe if I gave the system a bump of refrigerant, it might resolve the issue of low side going into -10" PSI (vacuum). what do you think? 

thanks

Max

[David C]

A restriction will typically cause pressures to equalize much slower. An overcharge you may see frost at the suction line. I would give it a half charge and see what happens. 

[max999]

^{Yes, pressures equalizes right away after the compressor shuts off and I don’t see frost at suction line. I have “dial-a-charge” so I will add 1/2oz and see what happens overnight. 
 current pressures are -4psi and 125psi , freezer still not at temp, it’s 16F}

^{Question, can I use frost at the suction line as way to identify if the system is overcharge ?}

[max999]

Can I charge the system until the suction line frost up instead of adding just 1/2oz.?  This way I know it’s  not undercharged.

[max999]

In the beginning of the problem with my dual evap fridge I had a suspicions that the  problem could be with the 3way valve.  Can we say now,  that this is not the case and that the 3way valve is operational and function as it should. ?

[David C]

I Personally would braze in a new drier, vacuum, and recharge.  

Edited October 7, 2021 by David C

[max999]

Yes I will go ahead and do that.

btw about the frost question, why can't use this method to charge a system.? 

and you don't think I have an issue with the 3way valve, maybe stuck in one position? 

[max999]

 

sorry about all these question, I just like to understand what is going on first. thanks

BTW, I forgot to mention that after charging the system the low side went into vacuum again. so there maybe a floating restriction as you indicated. 

A while a go I had an issue where the freezer evap capillary tube had ice up and I was able to dislodge the ice by applying heat and allowing the liquid refrigerant to flow again.

can you explain when I apply heat to the condenser I was able to get the low pressure moving from 10" PSI vacuum back to positive pressure.? 

[max999]

Not sure if this is important or not , but after apply heat,with hair dryer,  to the fridge condenser , the low pressure went up from 10" vacuum to positive pressure and the freezer started to cool again from 28 to 20F within 20min of applying heat to condenser. is this still indication of a restriction, or is it something else?

[David C]

11 hours ago, max999 said:

btw about the frost question, why can't use this method to charge a system.? 

Some people do it that way. But not the right way in my opinion.

[max999]

Ok , I replaced the filter drier ,vacuum ,charged it using the suction line frost method, and it worked just right. 

Now , the low side does NOT go into vacuum , but the freezer is not reaching set temperature of 0F , it only reaches 11F and then move back up to 29F when it is defrosting mode, the fridge works fine it is always in the range of 37-40F.

is it possible that the defrost heater thermostat not coming on at the right temp. The marking on this themostate say: L48-30F . I went into the diagnostic mode to see if it open or close and it was close(01) at the 14F  (i.e 01=close 02=open), the pressures are 5PSI and 140PSI

 

thanks

max