Overheating/fluctuations with vintage air.

[Smokey burnouts]

If you've seen all the recent post I've made about having temp problems.... You know I've been chasing this for a while!! Well 2 radiators, 2 thermostats and lord knows how many trial and errors with other ideas I finally have a steady temp gauge at a safe temp.

What I have discovered is that in order for the system to work right I have to leave the tempature selector (on factory non ac controls w/ vintage air kit) on the "heat" position If I try to run the AC or even leave the selector in the "cool" position the electric valve cuts off the coolant flow to the heater core which then I think is creating a vacuum and causing the system to surge and have temp spikes.

I'm not sure if the vintage air kit is working/installed correctly or is this a common problem? Any guys running the vintage kit have any ideas??

Thanks
Daniel

[Ozzy2013]

I just installed one haven't fired the motor yet very interested in the outcome of this one!

[hemi43]

How much 134A was installed? Vintage air does not run conventional low side pressure, and someone not familiar with the system could easily over charge it. Only 1.8 LBS of refrigerant is needed, which would put the low side pressure in the 10-15 PSI range, where most vehicles run 30PSI.
Not saying this is your problem, but it's a good place to start.

[Smokey burnouts]

Originally Posted by hemi43

How much 134A was installed? Vintage air does not run conventional low side pressure, and someone not familiar with the system could easily over charge it. Only 1.8 LBS of refrigerant is needed, which would put the low side pressure in the 10-15 PSI range, where most vehicles run 30PSI.
Not saying this is your problem, but it's a good place to start.

No clue bout the 134... System was on the truck when I got it. Air blows cold about (40-50*) when the ac is running so guess it's ok...?

Is it normal or correct for the flow to be cut off to the heater core? Seems like it would def cause issues with the engine trying to pull water out/through the other end of HC.

[hemi43]

Sorry, I thought your problem was with the cooling side of your Vintage Air system. If you try and explain exactly what the issue is, I'll try and help you out because I've installed a few of these units with great success.
When you say "temp spikes", are you referring to the air coming out the vents when in "heat" mode? Having the heater hoses reversed could cause this. Make sure the shut-off valve is located in the coolant supply hose going to the heater core, and not the other way around.
It is normal for that valve to shut coolant off. That's what it's designed to do.

[ClassicStyle]

It should absolutely cut flow to your heater core.

If you have temp spikes and temp variations you have air In your system. Turn the heater on to open the hear core and burp the system, you might have to park with the truck pointing up a incline.

[Smokey burnouts]

Thanks Hemi and Classic I will check all that out here shortly and report back.

Hemi... I'm meaning temp spikes and problems with engine temp.

[Smokey burnouts]

Ok parked truck on prolly a 20° incline, made a burpee bottle and let the truck run for prolly 30min switching between heat and air, idle, under throttle and squeezed the top hose prolly 100 times even shut truck off Abe back on. I got a a handful of air bubbles and a few surges and when temp and water levels seemed to be steady I took it for a ride. 5-7 min in with air on.... Temp shot up to the red until I switched it to heat and it went right down.

I noticed when burping the engine, if I turned AC on after a min or so you can see and feel the top hose "surging/pulsating" kinda.

Took pics to make sure hoses are correct:

[Smokey burnouts]

Just a thought..... Switch the return hose off the WP to the radiator??

[hemi43]

Originally Posted by Smokey burnouts

Just a thought..... Switch the return hose off the WP to the radiator??

If you're having engine temp problems, then disregard the coolant hoses going to the heater. They have nothing to do with the engine cooling circuit.
Most issues I've encountered with insufficient cooling is related to air flow across the radiator.
Do you have a mechanical or electric fan?
Here's the important one-->Do you have a proper fitting fan shroud?

When does the truck overheat? Idling ? Cruising? highway speed?

[Smokey burnouts]

Originally Posted by hemi43

If you're having engine temp problems, then disregard the coolant hoses going to the heater. They have nothing to do with the engine cooling circuit.
Most issues I've encountered with insufficient cooling is related to air flow across the radiator.
Do you have a mechanical or electric fan?
Here's the important one-->Do you have a proper fitting fan shroud?

When does the truck overheat? Idling ? Cruising? highway speed?

It's an mechanical fan with a shroud that prolly fits good enough. Is not a stock shroud but was on the truck when I got it. I am only having issues with the truck running hot when I run the AC and block the water entering the HC via the vintage air electric valve. Other wise the temp sits low(180) and steady as a rock!! That's why I'm so concerned with the hoses to and from heater core.

Truck normally get hot (only with AC on)when I am pulling up to a stop or coming off the throttle. Usually giving it some decent throttle it will send needle back to left. That's why I think cutting off the water into the HC but allowing the water pump to continue to try to draw/circulate water out of the heater core is causing issues.

[hemi43]

Well, if it was my truck, I would ditch the mechanical fan and put on an electric unit.
Flexalite makes an electric fan/shroud combo that will most likely fix your problem.
I used the Flexalite 180 in my street rod which was also equipped with a Vintage air system, and never once did the engine ever go above the rating of the thermostat.

[ClassicStyle]

The Mechincal fan might not be sufficient when the a/c is running, condensors get hot.

Does it run hot with the air off? Edit- if it's getting hot coming to a stop or slow speeds wth the a/c on I'm lead to believe the mechanical fan isn't providing enough air flow to cool the condensor and radiator, once you speed up the air flow across the two increases and the truck cools down.

[Smokey burnouts]

Originally Posted by ClassicStyle

The Mechincal fan might not be sufficient when the a/c is running, condensors get hot.

Does it run hot with the air off? Edit- if it's getting hot coming to a stop or slow speeds wth the a/c on I'm lead to believe the mechanical fan isn't providing enough air flow to cool the condensor and radiator, once you speed up the air flow across the two increases and the truck cools down.

Yeah I'm starting to agree with ya there, maybe need better fan or electric one as a pusher for help

The reason for the electric valve in the line is to stop flow into the HC because the AC cooled air passes through the heater core?

[ls1nova71]

Originally Posted by Smokey burnouts

Yeah I'm starting to agree with ya there, maybe need better fan or electric one as a pusher for help

The reason for the electric valve in the line is to stop flow into the HC because the AC cooled air passes through the heater core?

Does your A/C always blow cold even when not moving? If you're not pulling enough air across the condenser your head pressure will rise and if it gets too high the compressor will shut off. I have always used mechanical fans on truck swaps and they cool fine, I can't imagine that that fan won't pull enough air providing you have a decent shroud. Putting a pusher fan in front will block the air you're trying to pull through the condenser and radiator. Edit: When you say mechanical fan, do you mean stock type clutch fan or some sort of cheap flex fan? A factory A/C truck clutch fan is the one I would use.

And for your second question, yes, the valve shuts off the water to the heater core because the heater core and evaporator are stacked together, so air is always blowing through both of them, unlike an OEM system that has blend doors and separates them. That is the price you pay for making the unit small and compact. It's also the reason your windows will fog up if you run the air, then switch to heat.

[Ozzy2013]

Did you call vintage air yet?Seems to me the compressor shouldn't make any noise if the pressure gets too high its supposed to kick out .I would be giving them a call in addition to running a electric out front and a regular fan and shroud on the inside .Thats my plan anyway last 4 trucks i built were done that way used a trinary switch and all was well .

[Smokey burnouts]

Originally Posted by Ozzy2013

Did you call vintage air yet?Seems to me the compressor shouldn't make any noise if the pressure gets too high its supposed to kick out .I would be giving them a call in addition to running a electric out front and a regular fan and shroud on the inside .Thats my plan anyway last 4 trucks i built were done that way used a trinary switch and all was well .

Think your getting me mixed up with another thread I saw about a noisy compressor, mine is doin good!

[Smokey burnouts]

Originally Posted by ls1nova71

Does your A/C always blow cold even when not moving? If you're not pulling enough air across the condenser your head pressure will rise and if it gets too high the compressor will shut off. I have always used mechanical fans on truck swaps and they cool fine, I can't imagine that that fan won't pull enough air providing you have a decent shroud. Putting a pusher fan in front will block the air you're trying to pull through the condenser and radiator. Edit: When you say mechanical fan, do you mean stock type clutch fan or some sort of cheap flex fan? A factory A/C truck clutch fan is the one I would use.

And for your second question, yes, the valve shuts off the water to the heater core because the heater core and evaporator are stacked together, so air is always blowing through both of them, unlike an OEM system that has blend doors and separates them. That is the price you pay for making the unit small and compact. It's also the reason your windows will fog up if you run the air, then switch to heat.

Yes my air seems to blow good and cool at all times. I'm running a stock fan and clutch to my knowledge... It's def not a flex fan or any other fancy aftermarket type set up. The shroud I believe is off a different yr GM something cause it doesn't bolt up to the rad hold downs like ours should but it fits all across the rad and pretty close to burying the fan blade halfway(maybe a lil shy of it).

[Ozzy2013]

Originally Posted by Smokey burnouts

Think your getting me mixed up with another thread I saw about a noisy compressor, mine is doin good!

Yup your right sorry about that was following two threads the other guy had compressor noise when it was overheating .

[ClassicStyle]

I agree that your a/c should warm up if the condenser isn't gettig cooled. Do you have any shop fans or something you can put in front of the truck while idling see if increased air flow at idle stops the overheating?

If you decide to go electric Id run pullers instead of pushers. But pushers arent the end of the world. A lot of new bmw's run both.

You are exactly correct on the heater valve. The majority of current oem hvac boxes have both the heater core and evap stacked In the same area. That changes if you have dual climate control but The biggest difference isthe ability to pull in outside fresh area vs VA recirc only. I actually prefer recirc, a/c systems remove heat, no better way to remove heat from the inside of a truck than pulling and cooling the air inside the truck. It was 117 degrees in arizona yesterday, I want remove heat as quickly as possible from inside the cab

[bamachem]

Check your flow via hose connections. Maybe the hoses aren't connected properly and you're really not getting any/much water flow through your radiator. When you shut off your heater core, then you block off your only means of rejecting heat.

You definitely have a water flow issue at the radiator. You just need to figure out why.

[Smokey burnouts]

Originally Posted by bamachem

Check your flow via hose connections. Maybe the hoses aren't connected properly and you're really not getting any/much water flow through your radiator. When you shut off your heater core, then you block off your only means of rejecting heat.

You definitely have a water flow issue at the radiator. You just need to figure out why.

That's what I was thinking that when I block off the supply to the HC the system starts acting up.

Riddle me this.... When The supply hose to the heater core is closed(using VA valve) and the return side is still connected to the water pump/return in rad(is equipped).... What happens to the water in the heater core is it sucked out of the heater core and now the heater core is empty or does the water somehow stay in the HC? What I'm thinking is the physics if you pull water out it has to be replaced by something right?

[ClassicStyle]

If you have no air in the system, it can't suck anything but water. I'm sure it creates some vaccum but it can't pull coolant out of it if there isn't any coolant to replace what is pulled out. Heater control valves have been mounted like yours since the dawn of heaters literally millions of cars. Your truck is overheating, the heater being on is just giving it the edge it needs to maintain a acceptable temp. If it's not the a/c then it is a flow restriction or your fan and or shroud isn't suffiencient.


Have you replaced your coolant temp sensor recently? I've seen the wrong sensor cause mis diag of overheating. Just food for thought.

[bamachem]

Originally Posted by Smokey burnouts

That's what I was thinking that when I block off the supply to the HC the system starts acting up.

Riddle me this.... When The supply hose to the heater core is closed(using VA valve) and the return side is still connected to the water pump/return in rad(is equipped).... What happens to the water in the heater core is it sucked out of the heater core and now the heater core is empty or does the water somehow stay in the HC? What I'm thinking is the physics if you pull water out it has to be replaced by something right?

The water doesn't flow. It will be at a higher pressure at the closed valve than on the return side of the core, but it will not be replaced by anything. Simply put, the water just sits there and doesn't move.

Path of Least Resistance.

The water flowing through the engine block and radiator is supposed to move with minimal restriction. Closing the heater core valve restricts that side flow stream, but not the flow through the block, so the water follows the path of least resistance and doesn't care about what's happening at the core or anywhere in that side stream at all.

Here's your flow paths as per the factory arrangement. It looks to me as if you're not moving enough water through your radiator.

Have you replaced the thermostat?

If the thermostat was stuck closed, it would inhibit flow to the radiator, but you would still get flow through the block and to the heater core. The surging you are seeing at the upper hose could easily be boiling coolant from the overheating block where the coolant is touching the housing at the thermostat. It is not necessarily indicitive of flow, but really is indicitive of the LACK of flow...

[Smokey burnouts]

This is all great advise but honestly at this point I'm stumped how just the simple closing of the HC valve can cause the engine temp to rise 30+ degrees. The valve open and NO blower motor on the truck will run all day at 180*( barely off the min operating range on gauge).

Pulled in and been sitting in parking lot idling for prolly 10 min after driving around a bit and got the AC on(blowing 45-50* air) and needle hasn't gone above half way on the gauge.

Start city driving and needle is back and forth from H to C (within "operating range" marks on gauge)

To answer questions.... 1. Yes thermostat has been replaced, and seems to hold steady temp of 180(with HC valve open/no blower running)
2. Just put new temp sensor in other day and it's appears to move and hold gauge correctly