bosch wvd2452 gb/01 dryer fault

The dryer is not condensing, i have cleared any fluff from condenser, heater is ok (inc insulation), valves check out ok. there is only power to the condenser valve for a short period at the start of the drying cycle (auto 2 hours), at this point water trickles through ok. before the cycle even has time to really heat up, the power to the valve stops and does’nt seem to come back on until the cool down period. the heater cycles on and off throughout the cycle and steam comes out of the soap drawer as it is not being condensed. it then breaks the time remaining down and stops the cycle early, the towels are left warm and still wet.
Am i missing something or does this have to be a module fault !