Finally have HVAC down to one issue: No heat.
#1
Finally have HVAC down to one issue: No heat.
After years (literally) of chasing this ghost, we fixed 90 percent of the problems by buying this: https://www.jag-aire.com/copy-of-ja-16-details-1
That fixed the A/C issue, the compressor cut on/off issue, a whole bunch of stuff with the servo, etc.
What it didn't fix was the heater. The heater core is getting hot. But we can't get hot air through the vents.
Is there a blend door or something that could be stuck? If so, what are our options for fixing it? I'm not above tying a string to the thing when I want it opened, seriously. I would like, above all else, to avoid removing the dash to fix this.
Jess
That fixed the A/C issue, the compressor cut on/off issue, a whole bunch of stuff with the servo, etc.
What it didn't fix was the heater. The heater core is getting hot. But we can't get hot air through the vents.
Is there a blend door or something that could be stuck? If so, what are our options for fixing it? I'm not above tying a string to the thing when I want it opened, seriously. I would like, above all else, to avoid removing the dash to fix this.
Jess
The following users liked this post:
Andy Paine (12-01-2018)
#2
check the Heater Valve operation:
open hood / bonnet
run the engine until warmed up
move the mode selector switch to AUTO.
with a second person moving the TEMP knob from 65 to 85, watch the mechanism of the heater valve to see if it moves open / close. You can see a "lever" moving as you move the TEMP knob.
if it actuates open / close, the heater valve is fine.
at the same time, can you hear the SERVO whirring as it closes and opens Flaps from cooling to heat?
and of course the silly things: is the coolant level correct?
open hood / bonnet
run the engine until warmed up
move the mode selector switch to AUTO.
with a second person moving the TEMP knob from 65 to 85, watch the mechanism of the heater valve to see if it moves open / close. You can see a "lever" moving as you move the TEMP knob.
if it actuates open / close, the heater valve is fine.
at the same time, can you hear the SERVO whirring as it closes and opens Flaps from cooling to heat?
and of course the silly things: is the coolant level correct?
The following 2 users liked this post by Jose:
Andy Paine (12-01-2018),
JessN16 (12-01-2018)
#3
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,920
Received 10,978 Likes
on
7,211 Posts
Yes.
The system is designed to refrigerate all incoming air first and then heat it as needed. When cooling is called for, a door prevents air from passing thru the heater core. When heating (or blending) is called for, the door opens so the refrigerated air can be heated.
Also, when heating is called for, the servo operates the linkages and flaps to divert almost all of the air to the foot well outlets. Is this happening on your car?
Since your heater core is getting hot it suggests the heater valve is OK but do check it as Jose describes just to be sure.
When you select "defrost" do you get any hot air?
Lots of things to check for and different jumping-off points. But, you gotta start somewhere so I'd remove the console cheek panel and, while exercising the control from cold to hot, observe all the linkages and levers in operation. Does anything look stuck/binding/broken?
Cheers
DD
The following users liked this post:
JessN16 (12-01-2018)
#4
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,920
Received 10,978 Likes
on
7,211 Posts
#5
also: hanging next to the battery there is a one way ball check valve inline with the vacuum hose that connects to the servo. This plastic black and white valve tends to clog with time affecting the a/c and the heater system.
remove it and blow through it. Air should escape one way but not the other. If clogged, the ball inside won't move. Put it in a pan of warm water to try and unclog it.
before removing it, observe the orientation of the arrow marking on the valve body.
remove it and blow through it. Air should escape one way but not the other. If clogged, the ball inside won't move. Put it in a pan of warm water to try and unclog it.
before removing it, observe the orientation of the arrow marking on the valve body.
#6
check the Heater Valve operation:
open hood / bonnet
run the engine until warmed up
move the mode selector switch to AUTO.
with a second person moving the TEMP knob from 65 to 85, watch the mechanism of the heater valve to see if it moves open / close. You can see a "lever" moving as you move the TEMP knob.
if it actuates open / close, the heater valve is fine.
at the same time, can you hear the SERVO whirring as it closes and opens Flaps from cooling to heat?
and of course the silly things: is the coolant level correct?
open hood / bonnet
run the engine until warmed up
move the mode selector switch to AUTO.
with a second person moving the TEMP knob from 65 to 85, watch the mechanism of the heater valve to see if it moves open / close. You can see a "lever" moving as you move the TEMP knob.
if it actuates open / close, the heater valve is fine.
at the same time, can you hear the SERVO whirring as it closes and opens Flaps from cooling to heat?
and of course the silly things: is the coolant level correct?
Jess
#7
Yes.
The system is designed to refrigerate all incoming air first and then heat it as needed. When cooling is called for, a door prevents air from passing thru the heater core. When heating (or blending) is called for, the door opens so the refrigerated air can be heated.
Also, when heating is called for, the servo operates the linkages and flaps to divert almost all of the air to the foot well outlets. Is this happening on your car?
Since your heater core is getting hot it suggests the heater valve is OK but do check it as Jose describes just to be sure.
When you select "defrost" do you get any hot air?
Lots of things to check for and different jumping-off points. But, you gotta start somewhere so I'd remove the console cheek panel and, while exercising the control from cold to hot, observe all the linkages and levers in operation. Does anything look stuck/binding/broken?
Cheers
DD
The system is designed to refrigerate all incoming air first and then heat it as needed. When cooling is called for, a door prevents air from passing thru the heater core. When heating (or blending) is called for, the door opens so the refrigerated air can be heated.
Also, when heating is called for, the servo operates the linkages and flaps to divert almost all of the air to the foot well outlets. Is this happening on your car?
Since your heater core is getting hot it suggests the heater valve is OK but do check it as Jose describes just to be sure.
When you select "defrost" do you get any hot air?
Lots of things to check for and different jumping-off points. But, you gotta start somewhere so I'd remove the console cheek panel and, while exercising the control from cold to hot, observe all the linkages and levers in operation. Does anything look stuck/binding/broken?
Cheers
DD
That also means I haven't tested what the servo is doing with the vent control yet. Prior to yesterday, when they installed the switch, every vent on the car blew air. The shop didn't indicate things had changed, there.
I've never seemed to get any hot air anywhere, defrost vents or otherwise.
The one thing the shop did mention is that with the switch installed, the system is *trying* to respond to changes in the temp control wheel when selecting different temperatures. With the fan switch at AUTO, the fans were increasing/decreasing speed in response to inputs on the temp wheel. Until now, the car would do that in some cases and not in others. Obviously I'll have to drive it for awhile to see if that issue is going to remain intermittent.
At least it doesn't seem to be doing what it used to do -- going haywire and only wanting to function with the mode switch set to "DEF."
Jess
Trending Topics
#8
also: hanging next to the battery there is a one way ball check valve inline with the vacuum hose that connects to the servo. This plastic black and white valve tends to clog with time affecting the a/c and the heater system.
remove it and blow through it. Air should escape one way but not the other. If clogged, the ball inside won't move. Put it in a pan of warm water to try and unclog it.
before removing it, observe the orientation of the arrow marking on the valve body.
remove it and blow through it. Air should escape one way but not the other. If clogged, the ball inside won't move. Put it in a pan of warm water to try and unclog it.
before removing it, observe the orientation of the arrow marking on the valve body.
If that check valve sends some kind of vacuum signal back to the A/C brain, I'll look into it.
Jess
#9
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,920
Received 10,978 Likes
on
7,211 Posts
Does this check valve directly (and only) affect operation of the heater valve at the firewall? If so, that system is no longer; it's all controlled by a manual ball-and-lever valve.
If that check valve sends some kind of vacuum signal back to the A/C brain, I'll look into it.
Jess
If that check valve sends some kind of vacuum signal back to the A/C brain, I'll look into it.
Jess
The system does depend on vacuum supply to operate some of the doors and flaps so, yes, check the check valve for correct operation and make sure it is getting vacuum....which comes from a vacuum canister tucked into the LH inner fender near the firewall.
Cheers
DD
The following users liked this post:
JessN16 (12-02-2018)
#10
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,920
Received 10,978 Likes
on
7,211 Posts
I don't think compressor cut-out is the intended operation of the switch.
The switch is intended to replace the amplifier. The amplifier is the 'brain' of the system which, using sensor inputs, provides automatic fan and temp control. The amplifier, gives commands to the servo.
The servo might be called the 'robot' of the system. It mechanically operates the flap linkages, vacuum switches, and fan speed switches.
My understanding of the switch is that selecting warmer or colder should result in the servo operating just it would if being commanded by the amplifier. So, when changing from warmer to colder with the new switch you should hear the servo whir, the flaps flapping, etc
Cheers
DD
#11
I don't think compressor cut-out is the intended operation of the switch.
The switch is intended to replace the amplifier. The amplifier is the 'brain' of the system which, using sensor inputs, provides automatic fan and temp control. The amplifier, gives commands to the servo.
The servo might be called the 'robot' of the system. It mechanically operates the flap linkages, vacuum switches, and fan speed switches.
My understanding of the switch is that selecting warmer or colder should result in the servo operating just it would if being commanded by the amplifier. So, when changing from warmer to colder with the new switch you should hear the servo whir, the flaps flapping, etc
Cheers
DD
The switch is intended to replace the amplifier. The amplifier is the 'brain' of the system which, using sensor inputs, provides automatic fan and temp control. The amplifier, gives commands to the servo.
The servo might be called the 'robot' of the system. It mechanically operates the flap linkages, vacuum switches, and fan speed switches.
My understanding of the switch is that selecting warmer or colder should result in the servo operating just it would if being commanded by the amplifier. So, when changing from warmer to colder with the new switch you should hear the servo whir, the flaps flapping, etc
Cheers
DD
Jess
#13
Checked in with the shop today, felt like I'd been told it had a terminal disease.
First, to clear up something from earlier, the compressor is NOT turning off with the Jag Aire switch. It's not supposed to anyway, but something made them think it was earlier, and it wasn't.
They took out the glove box and disassembled the lower dash on the passenger's side to expose the linkages. The linkages do cycle with the Jag Aire switch. One of them (the one that is anchored most highly on the HVAC box) has a tendency to cam too far over and stick, and then must be moved back manually. Obviously that's going to be an issue when the car is put back together. We can't figure out what doors it changes, anyway. Maybe the fresh/recirc feature? Don't know.
They've gotten hot air to come out of the floor vents. That's progress, because we never have had that before. But when the system is set to full heat, I've got ice-cold air coming out of the dash and defroster vents unless you manually unplug the compressor. Then, you still don't get anything better than lukewarm air out of the face vents but again, I'll take it.
Nothing you do to the Jag Aire switch or the factory knobs allows you to direct air completely to the floor, dash or defroster vents. Air is coming out of all of them all the time.
In order to get hot air to the floor vents in Heat mode, you still have to close part of the system manually. Then when you shift back to A/C, it won't go back unless you manually send it back. So we're working on some kind of choke cable/manual pushrod to hook in there so I can manually cycle the system. We're also going to have to mount a compressor kill switch in the other ashtray. And then we still don't know what we're going to have when it's going down the road in cold weather.
Basically I think every part of the system is jacked. The amplifier was bad, and the Jag Aire switch fixed that, but either the servo and/or ALL the blend doors and actuators are also malfunctioning. We've already had to remove the factory heater core valve and put a manual valve in, and we've got vacuum issues in the system, too.
Combined with equally bad experienced with my system in my 89 Jag XJS (a D-III system), where I'm getting ice cold air in the footbox and hot air out of the defroster vents, you'll never hear me say anything nice about a Delanair HVAC system.
Jess
First, to clear up something from earlier, the compressor is NOT turning off with the Jag Aire switch. It's not supposed to anyway, but something made them think it was earlier, and it wasn't.
They took out the glove box and disassembled the lower dash on the passenger's side to expose the linkages. The linkages do cycle with the Jag Aire switch. One of them (the one that is anchored most highly on the HVAC box) has a tendency to cam too far over and stick, and then must be moved back manually. Obviously that's going to be an issue when the car is put back together. We can't figure out what doors it changes, anyway. Maybe the fresh/recirc feature? Don't know.
They've gotten hot air to come out of the floor vents. That's progress, because we never have had that before. But when the system is set to full heat, I've got ice-cold air coming out of the dash and defroster vents unless you manually unplug the compressor. Then, you still don't get anything better than lukewarm air out of the face vents but again, I'll take it.
Nothing you do to the Jag Aire switch or the factory knobs allows you to direct air completely to the floor, dash or defroster vents. Air is coming out of all of them all the time.
In order to get hot air to the floor vents in Heat mode, you still have to close part of the system manually. Then when you shift back to A/C, it won't go back unless you manually send it back. So we're working on some kind of choke cable/manual pushrod to hook in there so I can manually cycle the system. We're also going to have to mount a compressor kill switch in the other ashtray. And then we still don't know what we're going to have when it's going down the road in cold weather.
Basically I think every part of the system is jacked. The amplifier was bad, and the Jag Aire switch fixed that, but either the servo and/or ALL the blend doors and actuators are also malfunctioning. We've already had to remove the factory heater core valve and put a manual valve in, and we've got vacuum issues in the system, too.
Combined with equally bad experienced with my system in my 89 Jag XJS (a D-III system), where I'm getting ice cold air in the footbox and hot air out of the defroster vents, you'll never hear me say anything nice about a Delanair HVAC system.
Jess
#14
That is right, the jag-aire switch just replaces the amp and temp sensors. I have one in my 79. I strongly suggest adding a toggle switch that controls the compressor. Switch off = no cold air so you are halfway to better control. Your manual hot water valve is the other half. Yes, in heat mode the only air comming out is those tiny vents by your knees. Defrost gives you full a/c and full heat to the defrost vents. If you have total control over hot water and a/c compressor the defrost setting makes it easy to diagnose. Get a drawing of the levers under the left cheek panel. I checked my car against the drawing and discovered I was missing a little spring that pulled the rod back. Just keep studying the drawings and diagnosing and you eventually will get it working ok. Took me a whole summer but now it works ok (note I did not say like a modern car).
Jeff
Jeff
The following users liked this post:
JessN16 (12-07-2018)
Thread
Thread Starter
Forum
Replies
Last Post
stocksuspension
XJ XJ6 / XJ8 / XJR ( X350 & X358 )
6
05-09-2021 08:18 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)