A/C HVAC System Troubleshooting

[D Unit]

RESERVED.

Here's my attempt to document my troubleshooting experience regarding the A/C system from a self admitted novice with zero experience. I had a brief conversation with HitmanX who instilled some confidence in me, so here we go. I will add and edit the first and second posts as I go along, so it won't be perfect. I would appreciate any form of help as I go along.

What tools you need?
First off, you need to purchase an A/C manifold gauge + vacuum pump. I'm leaning towards buying this one from Amazon for about $129.
https://www.amazon.com/XtremepowerUS...tag=chri0e2-20

How to use the A/C manifold gauge and pump?
Next, you will need to check the vacuum system for leaks. The link below explains how to use the A/C manifold gauge + pump. On my car, all air flow goes through the defroster which indicates I have a vacuum leak somewhere.
https://www.youtube.com/watch?v=Pdq8JAlct6s

Where are all the vacuum pods located?
Pods can either be single or double stage but both are rebuildable. It is easier to rebuild the single stage ones. Before you can rebuild them, you will first need to purchase George Murphy's rebuildable diaphragms located here.
http://www.perfanalysis.com/climate-...cc-version-ii/
Here's DesktopDave's thread "how" to rebuild them.
http://www.bimmerforums.com/forum/sh...um-pod-rebuild

There are (2) HVAC pods located underneath the wiper cowl. One is single stage (white)... the other is two stage (violet/brown).
Use diagram below.

15	ACTUATOR FRESH AIR FLAP LEFT		1	09/1979		64111368347	$54.19	2 stage
16	ACTUATOR FRESH AIR FLAP RIGHT		1	09/1979		64111368348	$54.19

There are 5 pods located inside the cabin. Use diagram below.

No.	Description	Supp.	Qty	From	Up To	Part Number	Price		Notes
01	ACTUATOR FRESH AIR FLAP		1	09/1982		64111369309	$62.83
02	ACTUATOR REAR ROOM FLAP		1	04/1980		64111361836	$62.83
02	ACTUATOR REAR ROOM FLAP		1	04/1980		64111466190	$47.25		Rear passenger is not fun. You have to remove the center console to access it. Unless you are a glutton for punishment, just cap it at the vacuum branch. I removed mine to jam open that flapper door so I always have airflow to the rear seats on my 735i. This requires pulling the front of the heater box. Not as bad as it sounds once all the BS is out of the way. The rear seat one is usually bad too. Too spendy to repair... pod is $70 now. Just remove it and plug vacuum line at the vac tree. If you need rear air flow like me, jam a piece of 5/16" fuel line in the flapper to keep it open.
03	ACTUATOR DEFROSTER FLAPS		1	04/1980		64111368440	$62.83		The worst accessible one to me is the defroster pod above the driver's foot (LHD) as the damned HVAC brain is right in your way along with a pile of linkage for the system.
04	Actuator air recycling flap		1	04/1980		64111367830	$30.41		Last is the recirculation pod above the defroster... not sure if you could access it in the car. Maybe if the pedal box was removed? Maybe the column?
05	ACTUATOR FOOT ROOM FLAPS		1	04/1980		64111367818	$62.83
06	Valve		X	04/1980		64111376325	$44.73
16	Distribution Piece		1	04/1980		64111363061	$1.55		I believe this is the plastic T connector that HitmanX suggests to replace with a 1/8" brass one from Home Depot.

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NOTES...

E23 HVAC info
Rebuild HVAC pods:
http://www.bimmerforums.com/forum/sh...um-pod-rebuild
Buy diaphrams:
http://www.perfanalysis.com/climate-...cc-version-ii/

George Murphy
Performance Analysis Co.
969 Oak Ridge Turnpike, Suite 258
Oak Ridge, TN 37830

865-482-9175 9 am to 5 pm ET M-F
Chasing hvac vacuum leaks and vacuum diagrams.
http://www.bimmerforums.com/forum/sh...C-vacuum-leak&
Misc info: Search on e23 hvac pod
Yes, they are pretty easy to replace all things considered. I have many photographs of me doing this operation on my 735i.

Access to a few is a pain in the ass, but you could easily do the important ones that have failed in a day if you work fast and the ambient temperature is not similar to the surface of the sun. I work very slow... documentation, pictures, diagrams, bag fasteners, etc.

The worst accessible one to me is the defroster pod above the driver's foot (LHD) as the damned HVAC brain is right in your way along with a pile of linkage for the system.

The front footwell is also not too fun. The one just behind the HVAC controls is pretty easy to pull out... this is for the center vents. Wiper cowl pair are not bad, just a bunch of crap to disconnect prior to access.

Heater valve is a breeze.

Rear passenger is not fun. You have to remove the center console to access it. Unless you are a glutton for punishment, just cap it at the vacuum branch. I removed mine to jam open that flapper door so I always have airflow to the rear seats on my 735i. This requires pulling the front of the heater box. Not as bad as it sounds once all the BS is out of the way.

Last is the recirculation pod above the defroster... not sure if you could access it in the car. Maybe if the pedal box was removed? Maybe the column?

I suppose if you only needed vents to work you could just disconnect the defroster and center vent pods and the system would blow out of there.

Most of the single nozzle ones will be fine (sans water valve), it is the dual ones that fail most often as they are used more often. The water valve and defroster move every time the car is started and shut off, regardless of HVAC operation. i.e. if you leave the system off, they still cycle.

If water valve does not close, hot ass coolant flows through the heater core... which points to a vac leak. The H2O valve opens and closes all the time just like the defroster. The valve should close when you turn the car on, just have someone watch for it to move when you crank that bastard up.

I have the tech files here somewhere, if you want to know how the system operates PM your email and I will send the files.

Seriously, pull the dash out and pull vac on stuff. The rear seat one is usually bad too. Too spendy to repair... pod is $70 now. Just remove it and plug vacuum line at the vac tree. If you need rear air flow like me, jam a piece of 5/16" fuel line in the flapper to keep it open.



ok let me see if i got them all
2stage fresh in the cowl(violet brown?
single fresh in the cowl(white
heater water valve (red/green
footwell (dark blue
2 stage defroster(blue/white
recirc air(pink?
rear(black
fresh air(yellow

what does orange run to?
the white line and the blue line at the valve body work and hold pressure
and yellow leaks down fast until it hits 3inHg and sort of holds
orange is slower leak
none of the others hold any vacuum
my fresh air pods in the cowl work( the second stage in the one doesnt respond though
my heater valve is no good... can it be rebuilt? or just replaced

i know you say that the rear is somewhat a lost cause but can i even think about repairing the rest in the car or do i have to pull the box out?

the mityvac works like a charm
i have a new vacuum pump that is currently disconnected so that it doesnt pump endlessly
the vacuum bombs holds vacuum
all of the lines seem good but the pods seem no good

i have been digging through everything i can on the forums
i saw where the diaphrams can be bought....

thanks for any responses
if i do a pod rebuild i will try and document...
all HVAC pods rebuilt
so far everything works well
still trying to get to the AC test/rebuild stage
get the M-B diaphrams from performance analysis
george is great. resist the 2020s tho just get the 2010s.... the 2020s only fit the cowl double throw.... the rest just use the 2010s for....
oh yeah a car press makes the double throw repairs really easy


Behr designed these pods. The singles rebuild well, the duals not well. You have a few duals, wiper cowl, defroster, center vents.

Do not waste your time with the rear seat pod rebuild... if you want it to work, just remove the pod from the heater box and prop the flapper open.

Recirculation is a PITA to access. Do this when the defroster nozzle is out.
http://www.bimmerboard.com/forums/posts/135809

This is a pretty good diagram. There are actually 7 vacuum servos on the US 86 automatic HVAC system.
1. Fresh air flap, a two stage unit, is under the cowl, left side.
2. Fresh air flap stage 3 is under the cowl, right side.
3. Recirculating air flap is upper left side of HVAC unit.
4. Defrost flap servo, a two stage unit is just below #3 left side.
5. Footwell flap servo is underneath HVAC unit in front of heater coil.
6. Vent flap servo, a two stage unit, is in front of OBC.
7. Rear foot well flap servo is inside HVAC unit behind heater coil.
There are Eight - not 7 not 6 - There are 8 actuators.

two stage actuators on face vent, defrost and left side cowl.

When testing for leaks open the passenger side recirculate flap and you will see the 4 way tee. Apply vacuum and pinch off two circuits at a time to isolate which circuit is leaking.

The ETK shows the right and left cowl actuators reversed!

Keep in mind that many of the actuators are specific to manual or automatic HVAC systems and have different part numbers.

Tough jobs are face, defrost and footwell. Rear isn't worth doing.

For face actuator- drill the old and new actuators rivets and replace only the actuator and not the rod.

For defrost actuator- remove the HVAC control unit by gas pedal for better access.

For footwell actuator- two people with looong pliers and small flashlights.

BTW- the eighth actuator is the heater valve on the firewall.

The vacuum pods?

If your single throw ones are bad, they can be rebuilt provided the housing comes apart without exploding. The double throw do not rebuild well as the throw is reduced.

Do a search for me as the poster and HVAC, there is more information than you can imagine. I rebuilt mine last summer in the 735i. Not a hard job, just time consuming to test everything and find out what exactly is bad.

I need to check, but I think the cowl pods are a waste of money to replace. From what I remember, they are always open when the HVAC system is turned on and only close when the system is off... then they reopen when the car is switched off. I need to verify this for all settings, but I am pretty sure I observed this. If so, just plug all that stuff and save $100.

1. Oh hey, I also forgot to recommend to you to replace the POS factory plastic 'T' at the vacuum reservoir... I had a NEW one last right under three years. Pathetic. Find a brass 1/8" fitting, they are about $7 each. Same goes for the one at the auxiliary vacuum pump on the driver side.

That's a good idea I'll make sure I do that. Can anyone confirm the vacuum hoses. One out of the intake manifold goes to the check valve. Check valve tee, one to the vacuum res and the other side to the vacuum pump. I should really take a picture but if my son sees me go out to the garage he's gonna want to go back out.

Does your vacuum pump work? What I do is turn the car on, key on engine off, and listen to the vacuum pump running. Then one by one start crimping off one hose at a time starting at the pump itself working your way all the way into the dashboard. When you hear the pump start to work or turn off you know there is no leak, if the pump continues to run when you have crimped off a hose then you have a on that line.

Using a auxiliary vacuum pump will also work such as a Mighty Vac.


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Hitman's FYI/DIY - HVAC Diagrams and Pictures

Here are a few pictures I have collected over the years. I did not make the block diagrams, nor did I make the notation for the added ground for the late cars. The Sanden bracket is my scan from when I purchased my bracket around 2009 and the latest of the late E23 condensers that came about around 09/85 MY here in the US at least. Working on trying to find a picture of the normal US condenser and the comically small ECE one which is a single pass!

*obviously, this and all of my other FYI/DIY are a work in progress*




















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Adding attachments.

[Freshbread]

Badass

[Hit Man X]

I have learned some stuff since all of that, I did not post as was unsure if this was to be a DIY/FYI thread. Will post more this evening.

[D Unit]

Cool Eric. This is just a Fyi thread to gather information to one place.

Sent from my SM-N900V using Tapatalk

[madman2]

This a great asset, and will definitely help keep more e23s on the road. Well done.

Sent from my SM-G925F using Tapatalk

[Jay535is]

Excellent job

[Hit Man X]

First, need to specify this thread is for ACC found on all late US cars and most ECE cars. Some ECE have the more simple system and all their pods are single tit...plus 7/8 of them can be rebuilt with the Performance Analysis kit. The pod behind the door to the heater core can be used from a Mercedes W124 such as a 300E/400E/500E. Part 124.800.03.75 Current street price $32 versus $60 from BMW. $30 buys a nice steak and a sixer of beer.



Buy a better set of gauges and hoses, Yellow Jacket and Mastercool are both great. I use those brands for MVAC and HVAC work. Same goes for the vac pump.



Also buy a MityVac to test the pods. Honestly, you should just go ahead and rebuild or replace all. They are a minimum of 30 years old now at this point.



The cowl PNs (and pods) are reversed from RealOEM. The dual tit is driver side (LHD).



Dash removal NOT required to replace any in my experience. That is internet myth from arm chair mechanics that have never operated upon an E23 and bullshit shops.

Defrost is not too bad at all since I have done many more. I just remove the pod by cutting it off along with the rivet (use long pair of dykes) and keep the linkage attached to the heater box...I believe I reinstalled it with an M4x12 bolt with a washer a locking nut on the other side. I saw this trick on the front face pod (behind radio) in the junkyard and have implemented it ever since on many locations.

Recycle same deal... pull the defroster first and blend door stepper motor. Then cut the old pod off (yes it is a PITA) and do the same trick. Tightening it will REALLY test your patience, I advise at least removing the steering wheel. Even the driver seat if you are able to do this.

Face is a breeze once you are in there.

Cowls are a snap once in there too, be aware the hinged doors are fragile. You may want to consider permanently closing off the dual tit pod door and just using the single.

Heater valve under hood, best access ever!

Rear seating area not awful since you need the front of center console out anyway...plus the face is probably bad so go for it.

Front feet... ah fun times! Remove steering wheel to prevent bashing your head. I think I removed accelerator too, I forget. No real easy way to do it as you have to twist the pod to detach it from its bracket. I may have an easier way to do it, I will notify you guys within the next week or so after I try it if it works. I hope to hell it does.



Part 16 is that dumb ass plastic 'T' fitting. Do away with it there and by the vacuum pump with brass fittings. $10-15 and never a problem again.



Obviously, if your heater box is leaking at its attachment point to the firewall... then you need to pull it to prevent buckets of water from going into the cabin. This is very common on E23s from low mileage to extreme mileage. The foam seals simply degrade with age.

With it out, you will be able to access the pods easy enough. I can have one out, along with the dash, in around four hours best I recall working with help bagging fasteners.

If you go this route, replace the heater core with new OEM or full metal from Brassworks. Toss in the 09/85+ evap with matched TXV to help drop cabin temps faster, system charge remains the same at 1300 grams.

[D Unit]

Hey Hitman,

If I ONLY want the A/C to blow through the dash, do I still need to replace ALL 8 pods? If not, what's the minimum pods I need to replace?

[Hit Man X]

Hey Hitman,

If I ONLY want the A/C to blow through the dash, do I still need to replace ALL 8 pods? If not, what's the minimum pods I need to replace?

Front feet and rear area are of the least concern, so you would have six pretty much needed.

You could just plug off the vac supply at the vacuum tree to the remaining units that are bad. Hell, you can zip tie down the defroster linkage to keep it shut and pull the front face pod out toward rear of car...same with the cowls, just keep them shut. It will do what you want, but air will never recycle...so you could also zip tie down recycle linkage to prop the doors open. You will never have the cowls close to prevent cooling ambient air versus cooled cabin air (think AC versus Max AC in newer cars). Plus, heater valve will never close...so you will be fighting that also. Or you can bypass heater core for the summer.

I would want at least these working:

Heater valve, to shut off coolant flow to heater core
Face
Recycle

But would require quite a bit of 'creative' work, that takes time, to have the system work for the AC portion to cool the cabin well. Probably more hassle than making the six critical units function as designed. Really, it is not that hard to change these things out. Trying to make it work half-assed until you can fix it for real, will take quite a bit of dicking around that could be spent toward actually repairing the actual units.



What have you tested at this point? Are you just trying to limp through the summer with virtually no budget? I would just bypass the heater core, vacuum the system down, charge it with R152A so you have cooled, dehumidified air from the vents for now. Some cool air beats none.