Air blows hot with AC on, possible vents not switching?

[uhhair]

So it looks like my AC is working, but when it is on my vents still blow out hot air. I am guessing it is related to whatever mechanisms happen behind the vents to direct air from the heater core to the evaporator. I tried to do some searching here but I'm a little lost as to what the possible problems could be and how to troubleshoot it. I read a few things about a vacuum line, but beyond that I'm a little lost. Any help would be appreciated, thanks!

[DMC5180]

Hot water circulates through the heater core in All positions except MAX A/C. Verify Max A/C position does not allow heat. If it does you may have a faulty mode switch diaphragm. Also, reference the Delorean workshop manual HVAC section. It has descriptive charts that show what vacuum doors operate based on mode switch positions.

FYI, the Cold/Hot door is mechanical cable operated. Make sure it is set full cold.

If the source of your heat is by your right foot, that may be the common failed foam seal on the front side of the heater core housing.

[WHO1DMC]

The first thing I would check because it's easy is the hot water valve. The vacuum line can get weak and fall off or not hold proper vacuum to shut the valve or the valve could be bad. It's on the passenger side behind the engine.



Dave B.

[Helirich]

Both of these guys gave some good advice. Just to clarify your problem, is the air heated or just outside summertime air? The other question that comes to mind is how are you deturming that the AC works?

[uhhair]

Thanks everyone for your insight. From what I am feeling, the air is blowing hot, not just ambient warm air. At first I thought this was an AC issue so I did hook up all of my gauges and the compressor is engaging and working. Less than two years ago I converted the system to R134a and at that time replaced the lines, dryer, orifice tube, and compressor. It has worked fine up until this year. I also rebuilt my mode switch earlier this year, so for now I do not think that would be causing the issue. One little piece of information that may help, is that I have had the problem before where the air blew warm/hot and then the AC started to work. At first, I thought it was just taking the AC a very long time (maybe 10 minutes) to get cold, but then this problem if it not working at all started so I am thinking I was having an intermittent issue that has now failed completely. I am first going to check out the vacuum lines in the engine bay as suggested, since that seems to be the path of least resistance and go from there. Thanks!

[MrChocky]

This isn't an entirely helpful response to your question, but I think it's worth noting as something that can happen. There's a torn vacuum line on my project. I'm told this would only affect things with the Max setting. It'll be repaired of course, but there's no A/C hooked up right now.

PXL_20210716_183124154.jpg

[uhhair]

Well I figured it out! Turns out that there was a tiny screw on the control for hot/cold that came loose. I'm not sure what the part name was, but it was at the far end of the cable right by the airbox. Thanks to everyone for their help, now to figure out how to make this thing blow colder!