I have fitted a mitsubishi heavy industries SRK 40-HG has been working fine however it will not switch onto the heat mode.

check pressures low pressure is around 1.7 to 20bar when the comp running,and in the heat mode the 3/8 pipe work is getting very hot however the the blower unit will not blow air out warm air if i switch it to cool mode then the blower unit blows perfect nice and cool canyone please help
thanks
richie

trickie999@yahoo.com