Heater issue

[Dibzy13]

Just had my engine replaced, and it’s come back and the heaters don’t work. The fans work but only blow cold air even when the dial is turn max to hot. 

thermostate is working, electric water pump is fine, tried letting the engine idle to temp with the coolant cap off and climate reset.

got a feeling it’s the heater flap. 
but don’t want to replace it until I know what it could be. Would it flag up on a plug in diagnostic? 
 

[Warrior193]

Hello, welcome to the forum.

My money is on there being an airlock in the cooling system. You may be able to clear it with patience while keeping an eye on (and topping up) the expansion tank.

I'm not sure if it applies to your model - but my understanding is that there is a VCDS procedure to purge air from the cooling system after drain and refill - do you know if this was carried out?  

[Dibzy13]

The engine was fitted and topped back up, they weren’t a Skoda specialist 

[Austin 7]

Hi

 

I agree with Warrior193,  it's too much of a coincidence having the cooling system drained and refilled and then the heater not working.  Air lock would be my first thought.  Cooling systems have got more complicated over the years, with control valves, multiple thermostats etc.

[Dibzy13]

I have requested a call back from the garage tomorrow so I will speak to them then as I’m not happy how the car was returned anyway. 
Things not put on properly, broken or even a dirty mechanic rag left in the engine bay. 👀

I won’t be using the garage again 

[red2]

When I partially drained and re-filled my cooling system, after changing a water pump, I was originally going to just top up and "burp" the system by squeezing radiator hoses, etc. running the engine with the radiator cap off ( as per traditional simpler cooling system practice ) but then the complexity of these cooling systems gradually dawned on me and I wasn't then comfortable with this method. I eventually bought a Draper vacuum filling system and did it that way. Under vacuum, I was able to get in an extra litre and a half of coolant if I remember correctly (compared to first running the car up to temperature with the cap off). Many of the manufacturers now seem to recommend vacuum filling. I didn't do any VCDS procedures but will probably look up and see what this entails since it has been mentioned above. 

Edited 7 February by red2