help please for frost sree fridge is warm

[scooper]

i have a whirlpool frostfree fridge freezer and the fridge compartment is warm,the freezer is mostly cold but sometimes defrosts and also goes warmer.

we have done things like take back part out and used hairdryer to defrost all ice and have made sure the seal on door is on properly

it works for tops a couple of days then goes off again

any advise is really great

thanks

[tonto33]

thermistor failure

[scooper]

thankyou

are ther easy to fit yourself?