I had to change my entire dash out about a year ago and it all worked no problems, now that winter has come along, I've noticed that when I turn the rotary knob to red (for heat) I get none. The aircon works ok. Also when I checked that plunger switch arrangement behind the glove box, it works.

I really don't know whether the dash change out has ruined my heater, or if maybe it was a co-incidence and 'cos my El is old, that maybe the hoses are blocked or something.

I am quite sure the vacuum lines where all hooked up when I changed the dash out. I checked them multiple times before doing up all the screws along the windscreen sill inside and the ones on the floor in the centre and sides etc

Any ideas ?

Maybe the dash change-out had nothing to do with the heater not working, it's been almost a year since I used "hot". The fan works. Just no warm air!

The hot cold is cable operated... Not vacuum operated... So there is a cable and lever behind the glove box you should be looking for to see if it works...

The heater tap you can see operate down under the intake manifold with a torch... It might be broken (I threw mine away and replaced it with a barb to barb adaptor)... But easiest thing to check, is where the two hose go in through the firewall behind the intake manifold, grab them and make sure they're both hot... If one is hot and one is cold then your core is blocked... If they're both cold then something is wrong with the cooling system... If they're both hot then you have a problem in the heaterbox...

Cheers,
Tim