When you turn your AC on to “Heat” mode, the heater valve opens up (sometimes motorised, this time its a physical linkage alike the throttle cable) and allows hot coolant into the heater core, which air is forced through, to provide hot air into the cabin.

The off the shelf hose option was $145 from Elusive Racing. While this does look the goods and is quality, my mum didn’t bear with 9 months of pregnancy for her son to go out into the world and spend more than $100 for a hose and some clamps.

This can be done by a curious DIYer for about $15. All I needed to purchase was a hose adapter and some length of hose, full parts required are

  • Heater valve (use your old one)
  • Old heater hoses and spring hose clamps
  • 1 Metre of 3/4 inch heater hose - cost me $9 from bunnings and I only used about half of it
  • 3/4” to 5/8” hose reducer - get an automotive branded one like Gates, the bunnings ones for garden hoses are not rated for the high heat of an engine bay
  • Hose clamps (use your old ones) - purchase one sized for the larger length of hose you bought

The hose inlets on the car’s side are all 5/8” like your old hoses, the outflow from the engine head is 5/8” as well, but the return is 3/4”. So technically if you want, you can just plug the input hose as-is, cut the outflow hose in half, adapt it to 3/4” and route it to the metal outflow, but I don’t like this because it leaves the heater valve a bit too close to the head for my comfort. I’d rather a neater look. What I did was;

  • Cut the 5/8” hose and use a section that tilts towards the inlet.
  • Mount the heater hose to it with the old hose clamps, check that the valve fully opens and closes - a trick for this is to keep the valve in the open position (cold setting on the AC lever), this is the furthest extended the cable will be, hot will pull the cable in, and pull the arm on the valve towards the car
  • Cut up a straight length of hose, mount it to the valve with the hose clamps
  • Find a similar piece of elbow hose for the outflow on the firewall, cut and mount it
  • Mount the hose reducer and cut the required length of 3/4” hose and route it to the outflow pipe

heater

Still waiting to get the hose reducer sorted hence it being taped together. The position of the heater cable is important, line it up so that when the cable is pulled, the handle moves in the same plane, and not at an angle, or else your valve wont fully open/close.

This cost me less than $20 and is a fully functional, and safe option