Heater questions

[nooblet]

Holy #(&! it got cold all of a sudden! My heater worked fine last winter, but now it doesn't want to work at all. Since heaters are pretty damn simple I started looking around for possible problems. I noticed the diaphragm valve on the line going from the manifold to the heater core, and it seemed like a good place to start troubleshooting. I assume that when you turn the controls from anything to "heat" that valve is supposed to open to allow hot water to run to the heater core. The valve is apparently run off of vacuum. The valve is not opening, so I took the vacuum line off and felt for vacuum. No vacuum. Since its #(^@ing cold outside I went with the ghetto fix and zip tied the valve open.

To my question:

1. Wtf is the purpose of this valve? most vehicles I have worked on do not have this valve. I'm just shooting in the dark here, but it seems like the only reason you would need this valve would be if the fan blew on the heater core and the ac condenser at the same time. Is this how it works?

2. So if I leave the valve rigged open and use the AC will it be blowing hot air and cold air at the same time?

Thanks!
Chris

[PToombs]

1-Yes
2-Yes

The evaporator and the heater core are almost next to each other. You have to shut the water off for A/C, and vice-versa.
If you have no vacuum there, you may have other problems too. The vacuum controls the doors on the heater unit; defrost, floor, vent. The fix may be as simple as the vacuum plug fell off the switch.

[wannadiesel]

The shutoff should only be closed in the "Max A/C" and "OFF" positions. Otherwise you have no way to control the air temp out the ducts. Air temp is controlled by how much outside air passes over the heater core before it hits the ductwork. All the way to the left - none, all the way to the right - all. If you use the A/C it will work as normal, but the "Max" setting will not be as effective.

[nooblet]

Thanks for the info as always guys! Looks like I'm going to leave it rigged up like that until I need to use the AC again. Once it warms up I'll troubleshoot the vacuum problem and get it all working properly.

Chris

[nooblet]

I'm going to bump this thread with a couple more questions. I'm having some really annoying heating/cooling issues. My A/C is all ghetto rigged to begin with (bypassed low pressure switch that the P.O. did, then I bypassed the clutch switch with a relay). My A/C leaks, but not too bad. I fill it with R-12 every 4 months or so when I use it all the time.

Here is my main problem though. My compressor squeals horribly when my truck is idling. I mean it squeals all the time, but you can only hear it over the engine at idle and up to about 1.5k RPMs. When you engage the clutch it squeals even worse. I've been told that the bearing inside the compressor is going out or is out and thats whats making the noise. I've also been told that oiling the system would oil that bearing. Is this true?

I'm not so worried about the noise as much as I am the compressor seizing one day and throwing the belt while I'm driving down the high way, as I'm sure most of you can attest our trucks are not the easiest to steer manually.

I'm thinking I might need to replace the compressor and convert it to R-134 and fix the leak (which I'm sure is at the evaporator core) all at the same time and get it done with. But I hear horror stories of these compressors costing $400?? Is that true?

Any help or advice would be appreciated.

Chris

[nooblet]

Thanks for the info as always guys! Looks like I'm going to leave it rigged up like that until I need to use the AC again. Once it warms up I'll troubleshoot the vacuum problem and get it all working properly.

Chris

Our winter in San Antonio is pretty much over with. But even with that valve rigged open my heater never worked. I think I have a vacuum problem. It takes a long time for my A/C controls to kick in, and sometimes they never do. When I switch the controls from heater to A/C it takes about a minute for the air to stop blowing from the floor and start blowing through the top vents.

Thats a vacuum problem right?

Thanks again

Chris

[flashgordon]

Yes.

Start with the Vac pump under inj pump bolted on the drivers side of the block. Check vac there, and work your way up following you lines.



Flash

[PToombs]

On the compressor, get a belt for a non-A/C truck, and bypass the compressor. The only difference is the belt routing, and the length of the belt. Then in the spring, take care of the compressor.
The plus side to this, you have a spare belt in case the compressor craps out, or you lose the regular one on the road.

[nooblet]

On the compressor, get a belt for a non-A/C truck, and bypass the compressor. The only difference is the belt routing, and the length of the belt. Then in the spring, take care of the compressor.
The plus side to this, you have a spare belt in case the compressor craps out, or you lose the regular one on the road.

I just read that some one else did that on another forum. I'm going tomorrow to get one of those belts.

Any info on the compressor? From what I've read its different from the IC'd trucks. I found one from autozone for about $200 but that is probably the wrong one right? If its the bearing on the clutch assembly making all the racket can I put a new clutch on the compressor? I saw clutches for sale for about $70.

Info for this compressor is as scarce as it is for my Dana 61

Chris

[nooblet]

Yes.

Start with the Vac pump under inj pump bolted on the drivers side of the block. Check vac there, and work your way up following you lines.



Flash

Sounds like a plan, thanks Flash.

Chris

[flashgordon]

I know the way the A/C line rought is a little fifferent.........but i thought the compressors were the same........Mybe not.......


I was re reading your post and you say that the belt squeals all the time and noise get lower with the a/c on right?

If the bearing in the a/c clutch is going bad then the noise would go a way with it engaged.

If the compressor was ready to shell out, then the noise would go a way when you turned the a/c off............

I think you have a bad tensioner or fan hub bearing.

Putiing the non a/c belt on would tell you if the a/c is at fault.

[TWorline]

Throwing the belt will not affect your power steering, it is gear driven.

[flashgordon]

Throwing the belt will not affect your power steering, it is gear driven.

Thats a good point,.........the head gasket won't Put up with the belt missing............for vary long

[nooblet]

Throwing the belt will not affect your power steering, it is gear driven.

Hrm, I should have known this

[nooblet]

I know the way the A/C line rought is a little fifferent.........but i thought the compressors were the same........Mybe not.......


I was re reading your post and you say that the belt squeals all the time and noise get lower with the a/c on right?

If the bearing in the a/c clutch is going bad then the noise would go a way with it engaged.

If the compressor was ready to shell out, then the noise would go a way when you turned the a/c off............

I think you have a bad tensioner or fan hub bearing.

Putiing the non a/c belt on would tell you if the a/c is at fault.

I was thinking about this the other day... I'm going to buy the non a/c belt just for this reason. I kind of always assumed the compressor was going out, but this is a cheap way to know for sure. The belt tensioner was quoted as being over $100 last time i checked

I guess its better than a $400 compressor though

Thanks guys, if you can think of anything else let me know!

Chris