Ac question

[6.2/1983]

I have a 1984 k5 blazer with the 6.2 diesel and I am trying to get the ac working on it. My wife has lupus and cannot ride in the hot weather without any ac so I took it to a shop.

They changed it over to r134a, and tested it. It holds a charge and doesn't leak however it only works on the floor mode.

They told me it was either the vacuum pump or the control unit.
He wanted 951$ for the pump, and did not tell me a price on the control unit.

I looked online and i can find the pump for about 150-200 ish. If it is the pump has anyone switched them and was it hard or did you need an ac machine to drain and refill it?
As far as the control unit is that just the little switches that move the positions, and is that an easy swap?

thanks guys.

 

[frankin5]

changing the vacuum pump or the AC control unit unit has nothing to do with the charge of Freon.. Check to see if you have vacuum at the pump, if not new pump. make sure all vacuum lines in engine compartment are good. It sounds like blend door is stuck in the floor mode. You need to see if a vacuum hose is bad under dash or a control cable is not working.

 

[imiceman44]

changing the vacuum pump or the AC control unit unit has nothing to do with the charge of Freon.. Check to see if you have vacuum at the pump, if not new pump. make sure all vacuum lines in engine compartment are good. It sounds like blend door is stuck in the floor mode. You need to see if a vacuum hose is bad under dash or a control cable is not working.

Agreed

 

[Blue85]

You might just have a vacuum leak. Test the output (input?) of the pump to see if it works. I've never done it, but assume you could feel the vacuum there even if you don't have a gauge. So there could be a massive leak such that you have no vacuum anywhere. (What else runs on vacuum and do they work at all? Cruise control? Recirc/fresh door). Or the line passing through the firewall could be leaking. Or there could be a leak in the lines under the dash. For that you'll have to trace them around. If there's any vacuum you should be able to find a leak with a stethoscope.

As a short term workaround you should be able to wire the mode lever into the "dash" position. It's mounted behind the dash on the side of the HVAC ducting. In really hot/humid weather having MAX (recirc) work is also nice so you could also wire the fresh/recirc door shut (behind the passenger kick panel).

The hot/cold selection (blend door) is mechanical and therefore shouldn't be affected by the vacuum issues.

 

[6.2/1983]

I just got it back today from the shop. It does blow cold air but it seems like its really slow, and it is coming out of the other vents when on max not just the floor.
However it is coming out the most on the floor setting when set to max.

They said it could be the pump/control unit/ or the lines. I feel like they did not want to go any further with this job so he said it would be 951$ for the part.
So that's where I am at with this.

Where should i check first? I was thinking of removing the dash and looking into the lines there and at the control unit.

Thank you guys for all of the help I really appreciate it.

 

[Blue85]

Where should i check first?

Don't like my ideas?

 

[6.2/1983]

Yeah I’m sorry. I was using the site from my phone and it ping pongs around on the site because of the ads. I did not see your reply sorry.

 

[Abusfullofnuns]

I’ve got a recirc question while we are on it. When I set to Max, it only changes mode when the throttle is applied. I haven’t looked behind the kick panel yet, but assume it’s a vacuum issue. Everything else works.

 

[Blue85]

So always apply the throttle. Done.