under dash heater,A/C unit

[Cbumpus9398]

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This is what my valve looks like.

[Cbumpus9398]

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This is where my break is.

[fireguywtc]

Looks like you have already torn into the system. You can use a new heater core from a non-AC heater. You will have to take it to a radiator shop and have them put the top tank off the old AC heater core and swap it onto the new heater core. The "core" size is the same for factor AC and non-AC heater cores.

If all your AC stuff was R-12 still and working fine, I would put R-12 back in it. If you want to change over to R-134a, I would recommend a larger condenser.

[Cbumpus9398]

That's exactly what the radiator shop did. They heated the top and bottom tank, removed it from the old core and soldered them back on the new core.
I do have R-12 with the original compressor. It has the original line valves at the compressor, so all I had to do was close the valves and hopefully the freon stayed in the compressor. It did leak from the lines but I'll know when I put it back together.
Now I need to try to repair or replace that line that's broke on that expansion valve.
The same guy that repaired my core says he can repair it. We'll see.

[fireguywtc]

You may have saved some R-12 in the condenser but it doesn't matter a whole lot. To ensure your AC system is running efficiently as possible after the repair, it will need to be completely vacuumed to remove moisture and then charged to the required weight (charge). To do that correctly,all the refrigerant will have to be removed.

[mustang68 ranger71]

The no heat at idle can be partly blamed on a clogged heater core most of the time. At idle the water flows through the system slower and the water in the heater core is cooled faster than it is replaced by fresh hot water. When the heater core is clean and flowing properly the heater core will stay full of fresh hot water and it will blow hotter. Now it will not be as hot at idle as it will going sown the road due to speed of water flow but it should be hotter than you are describing it is now.
To flush it just disconnect the heater hoses from the water pump and flush water through in the opposite direction that it normally flows. this will flush out most of the debris. if you want you can even zip tie a shop rag over the end of other hose just to see how much debris comes out. once you do this for several minutes you can do it in the other direction. but before you are done you want the last time you flush it to be in the opposite direction of water flow.
NOTE: do not start flushing it at full blast, gradually increase the pressure as you go. And you can tell if it is clogged by the flow of water coming through. if the flow starts to increase you can increase the pressure.

[Cbumpus9398]

It looks like I'm gonna need a new a/c evaporator from an add-on a/c under dash unit for my 1972 f100. Please help me find one, I'll need the hose that connects to the compressor. I think I can find the expansion valve. Please help me know what to do. Please. Charlie

[sargentrs]

Here's one on ebay. http://www.ebay.com/itm/68-69-70-71-72- ... 4897.l4275 A little pricey if you ask me. Anybody got an OEM part number?

[Busboy]

If your windows are fogging up it very well might be due to a slight leak in the heater core and the antifreeze is being vaporized on the windshield. The fact that your heater cools off at idle suggests that the core is partially plugged as well. The low idle rpm doesn't allow the water pump to push enough coolant through the core. Most factory climate control systems engage the a.c. compressor when the defrost mode is selected. This dehumidifies the air so that the windshield won't fog up. If this isn't the case on your aftermarket unit, it could be easily wired to do so.