A/C and Heat Mixer question

[Mitch]

Hello All,

Any experience out there on the following:
My A/C and heat work great. Very cold and very hot. Absolutly no mixing with the hot/cold slide bar.

I have a 66 town landau. Is there a typical problem (broken mixing door, or valve, or bad
heat/AC control unit) that I should start troubleshooting?

Thanks for your opinions.

Regards,

Mitch

[Joe Vandatta]

Mitch,
Hook up a vacuum gauge to the vacuum hose that goes to the water control valve. Set the control lever to off position. Fire her up---you should have no vacuum. Then, position the control valve to full on---you should have at least 15 in. If this cks. okay you may have a bad heater water control valve.
Since the control lever controls both heat and cold, you may have a problem there but the test mentioned will pretty much tell you if it is working properly.
Good luck,
Joe

[Mitch]

hello joe,

thanks for the place to start. I will try this in the coming weeks as the weather gets nicer.

regards,

mitch

[Harley Eaton]

Let me jump in here-- What do you mean by "control lever"? The top lever is MAX-FRESH-OFF-HEAT-DEFROST.. Where is "full on"?The lower lever is MIN-MAX...Where is "full on"? If you put the vacuum gauge on the hose to the water valve, MAX-FRESH-OFF will give you nothing with a working system. If you put the vacuum gauge on the water valve, HEAT-DEFROST will show a reading controled by the lower lever MIN-MAX. Low reading at MIN and higher reading at MAX. On the AC side vacuum goes to the AC thermostat switch.There is no "mixing" with these systems, only temperature control for the flow of hot water or for cycling the compressor. No vacuum to the water valve should give you no heat. It sounds like you are supplying full vacuum at all times. Harley ([email protected])

[Joe Vandatta]

I was refering of course to the heat-cooling lever which conrols both. The test is in the shop manual.