The heater on my Bf II xr6 is deciding to be difficult by working for a while then stop working for a couple of weeks. I was thinking maybe the HIM module needs replacing but the other week when the heater wasn't working, I was in my car idling away with the heater dial on hot but only cold air was coming out then i heard a clunk and then hot air started to flow out the vents. So maybe the issue is something to do with heater hoses blocking up.

Has anyone had a similar experience? and/or some advice?

P.S Mixer shafts are fine

single zone or dual zone
check both heater hoses are hot -does engine warm up (faulty thermostat maybe)
remove glove box
change heater temp and check white drive gear on side of HIM turns with temp change
check end of white drive gear just protrudes thru HIM as they had a habit of working out (push back in until almost flush with HIM)

no offence but how do you know mixer shafts are ok
they are the most common reason for heat problem and only easy to access at drivers side of heat box if single zone and able to watch end of shaft on drivers side of box but can be broken but turn via friction against the two ends being pushed together and slip next time it is operated

scan for codes and if done at Ford or someone with suitable scan tool run HVAC self test....

Cheers ror the advice, Its a single zone system.

Engine warms up fine doesnt over heat. Sits half way on the temp gauge.

I can see the mixer shafts moving when I turn the temperature side to side. Also the heater will start working randomly without touching the dial while the car is running. So to me that tells me its not the shafts as the mixer shaft wouldnt move 30 min after I moved the dial.

Ill check the white drive gear tomorrow and maybe swing by radiator specialist to see what they say about a flush of the system.