Heater tubes
 

Has anyone got a good diagram that shows where all the small hoses go for the heater etc up under the dash, there are 3 or 4 rubber hoses that have a different coloured tracer on the hose approx 5/16 or 1/4 in diameter they run from the heater assembly under the dash and some go through the firewall via rubber grommet.

What year? A/C or no A/C? It is usually shown on shop heater A/C manual.

Also, depending on the year of your car there may have been two different types of heaters available (Direct-Aire or Circ-L-Aire.)

Heater tubes
 

59 Catalina standard heater I think no air con, I can post pictures if that helps cheers

There are a couple pictures over on the pontiacsafari.com page that may be of help:

http://www.pontiacsafari.com/MPC/Pages/page_0496.jpg
http://www.pontiacsafari.com/MPC/Pages/page_0497.jpg

However, they don't appear to show the vacuum line connections. You'll probably have to wait for someone who has a 1959 HVAC shop manual to post pictures.

Pictures Stuart sent make the control look very much like the 61 Circ-L-Aire heater. This may help. But good luck if the vacuum control leaks . They are near impossible to get to seal up when they get old.

Heater hoses
 

Awesome thanks