Ford KA Heater working on full

[aka48]

Want to try and fix the heater on my friends 10 year old Ford KA
. It blows hot and cold air but only when its on full. Turn it to 1,2, or 3 and theres nothing. Sometimes it has worked but then went off.
Any ideas please

 

[merlin50]

sounds like the switch

 

[snaponman]

Want to try and fix the heater on my friends 10 year old Ford KA
. It blows hot and cold air but only when its on full. Turn it to 1,2, or 3 and theres nothing. Sometimes it has worked but then went off.
Any ideas please

Replace the rheostat/heater risistor. It is in the heater box with heater fan. Looks likes this.