AC questions

[fireguywtc]

I finally have AC working in the 70. It works pretty good but still needs some minor attention.

Does anyone know of a source for a material or how to insulate the metal hose connections inside the cab that connect to the evaporator? It is the wrap shown in the upper left pic below. It helps keep away the condensation and right now I have water coming down in the cab. The wrap I moved was very tar like and nasty.



Also does anyone have a part number or resource for getting new idler pulleys for the AC. I am not sure if mine are worn, but right now at idle I get a bad vibration in the belt that doesn't sound good under the hood. The pulleys are orginial and have sat for years and I am afraid they not turning like they are supposed to, although they are turning for the time being.

Finally, does anyone have any ideas on how to get the AC to blow colder. I have already have two valves to completely close of the heater coolant flow. I was also thinking of making a panel to block the incoming air vent from the cowel. That would baically make it a full time recirculation AC. I think I will have enough fresh air coming in from other avenues to compensate

I will try and update this page later on with some pics of what all I have done. If anyone has any questions, ask away!

[fordman]

70 f100 knows what that stuff is called. i forget wher ehe posted the name of it. they say to get a colder cool from the a/c that you should use a larger condensor in front of the radiator. because R134A takes more to cool down before it goes back into the evaporator. i dont know of any place that reproduces the idler pulleys for the factory air set up. if this is a 460 eninge then you may be able to get them from a newer truck or engine.

[fireguywtc]

The 70 has a 390 that I rebuilt, but it was all the orignial motor and hardware. I do have a larger aftermarket condenser that I adapted to it. When I get home from work I am going to put my small thermometer to see what temp is blowing out of the vents. It maybe that the evaporator is getting quite cold, but I may bet getting too much warm air from other places. Just theories at the moment.

It looks to be a really hot summer here in my area as we have already had 10 days over 100 and many others in the high 90s. (its not even summer yet) I am trying to keep my truck as comfortable as possible.

[BRUTUS_T_HOG]

ask for it at an autoparts store... hvac insulation... monkey poop... it has many names

[fordman]

my 68 with factor yair and r12 would cool the cab until the engine warmed up the cab. that was where my problem is. not enough cab insulation to keep the engine heat out of the cab.

[flyboy2610]

I've always called that stuff monkey crap. An auto parts store should have it.

[fireguywtc]

Thanks for all the help! I will check the auto parts stores.

[basketcase0302]

Bill,

This is what I'd always used to wrap TXV's in the field:
http://www.johnstonesupply.com/storefro ... 1-515.html

You want to make sure it's dry and clean and wrap the whole valve, (especially the diaphragm).

[70_F100]

Bill,

This is what I'd always used to wrap TXV's in the field:
http://www.johnstonesupply.com/storefro ... 1-515.html

You want to make sure it's dry and clean and wrap the whole valve, (especially the diaphragm).

That's the same stuff the factory used. I got mine from the local O'Reilly's, and it was something they actually had in stock.

I'll check today and get the part number off the box. I've got a BUNCH of it left, because I had to buy the whole roll.

[fireguywtc]

Jeff, thanks for the link. More importantly it made me think. I have a friend with an HVAC business. Perhaps he has some he can give me, so I will ask him first. It only make sense.

When I got home this morning I put my temp guage in the vents and driving around got me about 60 degrees out of the vents. However, when I stopped it dipped to 55. I am going to block off the incoming air to the box and see how it affects my temps.

Thanks all for the help!

[fireguywtc]

Okay, I completed my redneck AC recirculation. Which means I blocked off the fresh air vent into the AC box so now I only get air from inside the cab. I can only get my vent temps down to 60ish degrees. I was hoping for cooler, 50-55ish. What is weird is when I stop the truck it will start to cool a bit more, just below 60 to around 58. Does anyone have any advice on how to try and get the temps down? It is making it more comfortable then just windows down, but I would like to try and cool it off a bit more. I don't seem to be having too much warm air getting into the cab.

BTW, the guy who did all the charging of the system and such told me all of the pressures and everything else checked out fine. The only thing I can notice is that the AC belt is a tinsy bit lose (it vibrates when pump is engaged), but I cannot tighten it any more. There is no squealing or anything.

Just FYI, this old style of AC pump seems to take quite a draw of power from the motor. I would recommend getting the newer style AC pumps.

[70_F100]

I found that I needed a belt that was 1" shorter than the parts listing called for.

With the "correct" belt, I got so much belt slop that it sounded like the engine was coming apart at idle and I was embarrassed to run the A/C. I was able to eliminate that with the shorter belt.
The slop comes from the fact that it's a two-piston compressor and it's not as smooth as a rotary.

As for the condensation leaking onto your floor, check the shaft that comes out the bottom of the unit. There's a seal inside the unit on that shaft that disintegrates and lets condensation leak out. I just put a dollop of silicone on mine, and once it set up, it stopped my leak completely, without affecting the operation of the door.

BTW, if you find a way to get the temps down on yours, let me know the secret!!!

[fordman]

here is a guess. my factory air did the same thing. it was cooler when sittign still than when driving. but my guess is that the hot enigne air is forced against and through the cab in little places. when moving and not whent he truck is sitting still. that is what i always though. that is why i am goign to insulate my firewall to help keep engine heat away from the inside of the cab. you might be able to look fo rmissign firewall gromets or other holes that would let that heat into the cab area. also heat from the exhaust could be part of the problem too.

[fireguywtc]

I found that I needed a belt that was 1" shorter than the parts listing called for.

With the "correct" belt, I got so much belt slop that it sounded like the engine was coming apart at idle and I was embarrassed to run the A/C. I was able to eliminate that with the shorter belt.
The slop comes from the fact that it's a two-piston compressor and it's not as smooth as a rotary.

As for the condensation leaking onto your floor, check the shaft that comes out the bottom of the unit. There's a seal inside the unit on that shaft that disintegrates and lets condensation leak out. I just put a dollop of silicone on mine, and once it set up, it stopped my leak completely, without affecting the operation of the door.

BTW, if you find a way to get the temps down on yours, let me know the secret!!!

Interesting, it is good to know that the slop is fixable and I am not the only one. I was thinking the same thing, that I should just get a 1" shorter belt, but you confiming it makes it better!

What are your vent temps, have you measured?

here is a guess. my factory air did the same thing. it was cooler when sittign still than when driving. but my guess is that the hot enigne air is forced against and through the cab in little places. when moving and not whent he truck is sitting still. that is what i always though. that is why i am goign to insulate my firewall to help keep engine heat away from the inside of the cab. you might be able to look fo rmissign firewall gromets or other holes that would let that heat into the cab area. also heat from the exhaust could be part of the problem too.

I would have though that moving wouldn't affect the temps blowing inside the vents. That is where I am taking readings. Especially since I cut off all main supplies of ambient air. But who knows?

I am just trying to cool off the cab into the 70's. The outside temp right now is 104.6 in the shade. It has been like that for a week. I think its going to be a long summer I bet I am only getting my cab down into the high 80's, which atleast feels better then 104 with the windows down.

[fireguywtc]

Ac gurus, I need your help! I found out why my AC isnt getting very cold when I go down the road. There seems to be no regulation for the compressor and it runs all the time. We hooked up the gauges and the results seem to be the low side getting very low on the pressure when I rev the motor. As long as the truck is idling the pressures are perfect, but as soon as I rev the motor it gets out of wack.

How does the factory AC regulate pressures? What else do you all think I might need to do to get this thing working right? I know newer AC units have a high pressure switch on the dryer, but not mine.