RoccoCroce

This is my first post but I have a reputable forum account on crxcommunity.com under SanFranciscoTreat. (1990 CRX si DOHC ZC)

Ok so lets get to it.

2005 Civic LX Sedan (ES1)

The Obvious.

A/C system in good working order.
Good freon charge.
Good Pressure.
Filters pulled for diagnostic purposes.
Low Side at compressor ICE COLD when kicks on. Painfully cold..

The Issue.

No AC mixed into cabin airflow.


Other Notes

Majestic Honda Exploded AC View

All actuators respond to functionality.
Recirculation works.
When pulling EVAP SENSOR (#25), its ice cold.. As is the air that comes rushing out of the orifice it plugs into!! ( Driver Side Heater Sub Assembly - to right of fuse panel )

WITHOUT the AC, ( like in the winter that just passed )I've noticed when you switch to COLD on the rotary dial, it goes from like 100% Heater Core to like 85% Heater core / 15% Outside Air... So I'm assuming the SAME thing that's blocking the airflow over the evaporator coil / box / section of the heater box is the SAME thing that was restricting the "cool" / "non-heater-core" air into the cabin.

BUT....

I am aware that the HOT/COLD Rotary Blend **** actuates the blend also pulls sheathed cable that opens the water valve at passenger / center upper firewall mount. Having said that, Is it possible that there is NO bypass over the heater core to get to the evap and they're both running at the same time? This would mean my heater core is overpowering my evaporator.

I've notiecd its SLIGHTLY cool after a cold start and A/C running but it does NOT take long for that heater core to start kicking.

I'm a HUGE fan of the HVAC system in this car and its efficiency BUT I'm not so impressed by the mechanical actuation right this minute..

Conclusion.

Proper testing procedure for water valve? How long should it take for the air to switch back to nominal outside temperature after switching from HOT to COLD with AC OFF?

The water valve is also the "blend actuator / door" for Evap / heater?
This would mean it performs two functions- pulling sheathed cabled to rotate valve AND rotate a valve / diverter inside the Heater Sub Assembly ( driver side ) to divert air from Blower>Heater Core>Cabin TO Blower>Evaporator>Cabin.

Does it have a diverter that can stick or pop off or come undone?



I try to be thorough with my issues because there's nothing more annoying people no knowing what they're talking about when they ask questions.

Bro: "ay dawgs my **** dun work. don get cold no mo but hot doe"
Scum: "yea u need dat freon shot u got a leak it fxed my prob gl bruv. doe."
Me Cruising Through Forums:

I hope I've provided enough info. My original thought was replace the water valve actuator under the dash. I'm thinking if there IS a diverter though, its IN the Heater Core Sub Assembly... Hence a replacement wont fix anything.

First step for me is removal and inspection.

I will provide ANY pictures of information at request regarding this issue!
Help me help you to help me.

Anyone who comes across this, thank you for stopping to read and I appreciate your commentary as I'm new to the ES1 chassis.

Thanks again guys and gals,
Rocco

ezone

Welcome!

I have a reading comprehension problem, that's why I park in the wheelchair spaces.

So you have cold air at the evap core area OK, but not from the dash vents.
And you have too much heat.
Did I get that right?

I'll guess either a blend door/actuator issue or water valve issue.


Watch the cable and arm on the water valve. Have someone else move the temp dial from hot to cold.
The arm should have roughly 90 degrees of movement from closed to open (full cold to full hot).
If you have that much travel, then the blend actuator is probably working (with the fan on full blast you should also be able to hear changes in the air flow within the heater case as the blend door changes position).


I might disconnect the cable from the water valve in the engine compartment.
Manually confirm where the arm stops and compare to where the cable stopped at both ends of travel.


Get the engine warmed up, turn on the heater (hot) and fan full blast.

Manually (with your fingers) move the arm of the valve to the heat, or open position. Got heat?
Move the valve to the other position to shut off water flow to the heater core. Give it a minute for the blower to cool it down. Got ambient temperature air now?



If the water valve can't completely shut off the flow of antifreeze through the heater core, you won't get ice cold air at the vents.

RoccoCroce

Having responded to all of this, It's hard to believe ( still ) that the heater core could overpower the evap my air pressure alone and without any physical / mechanical diverter device PHYSICALLY restricting evap airflow.

I will pursue this in the daylight.

Thank you for the prompt response. I'm looking forward to resolving this.
Kinda wanted to take my car down the shore on Monday with my gal. ://

~Rocco

ezone

Yes, the cable is operated by the linkage between the actuator and the blend door.


By actuator I mean the electric motor that operates the mechanisms, also might be called a servo.

There can be many different names for the same item. I tend to use them interchangeably sometimes.

Blend door might also be called 'air mix' door, just as the actuator might be labeled 'air mix motor' in the service manual. If the cable moves when you change the dial from hot to cold, then the actuator MUST be moving.

If the arm of the valve makes about a 90 degree sweep, the actuator and at least part of its linkage is still working correctly. If it moves much less than 90 degrees, there is a problem somewhere.

Whether or not it is still operating the blend door inside the HVAC housing is yet to be determined (that's why I said to listen for change in air as the door position changes).

Ok.
You can DIY the checking positions at the top of that post where I said to have someone else turn the temp **** too. Just make note of the valve positions after you change the temp dial.

You leave the HVAC system set on maximum heat, then you manually shut off the flow of the hot antifreeze by closing the valve by hand (cable previously disconnected). You are removing its heat source this way.

If you still have heat output after a couple minutes then the valve is not shutting off the flow of hot antifreeze.




Already explained. The same actuator operates the blend door inside the HVAC housing.

You already know the AC works, you just need to figure out why the heat won't shut off.

Huh?


That would be the blend door.



I'm not sure why you are calling this air 'resistance' and 'pressure'.

The heater can always overcome the air conditioner.
You see this when you operate the defrost: The AC runs whenever the defrost is selected but you can always control the temperature as hot as you want.



The "doors" inside the HVAC system are simply opening and closing different air passages through the housing to direct air flow.

'Blend' or 'air mix' is the door(s) that control temperature.
'Mode' controls where the air comes out: Dash vents, floor, or windshield.
'Recirculate' controls outside/inside air flow at the blower fan intake.



ALL air entering the HVAC system must flow through the evaporator core.
If the AC compressor is running, the air is dried and cooled, then continues into the heater area.

If the temperature selected is "cold", then the conditioned air continues through to the vents without being heated first----because the blend door causes the air flow to bypass the heater core, and the heater core has no hot antifreeze flowing through it..
If "hot" is selected, the airflow is routed through the heater core to be heated using the hot antifreeze.






How'd that sound?

RoccoCroce

That's more clear. I don't mean to come off as stupid. It's a combination of ignorance / willingness to learn and slight aggravation. At the risk of looking uneducated, it DOES help me thoroughly learn and understand the problem.

I may not have clearly stated but I was having some doubts that there even WAS a "blend door". I know the actuator for it operated the water valve but that's only because I can SEE that.

I try not to assume anything with problems I am unfamiliar with. ( The EF doesn't have A/C )

Thanks to that beautifully coherent final paragraph of yours, I'm now convinced that the heat ISN'T shutting off rather than being convinced that the evaporator is being blocked off. ( As it seems unlikely the internal diverter would somehow dislodge or disconnect from the blend servo, rendering its internal mechanical position static- in this case.... HOT AS #@%^&@%#&^% MODE... )

I will, of course, go through all of the motions in the morning.

Again, thank you !

ezone

Understanding how something is SUPPOSED to work is key to figuring out why it doesn't work.

If you want to visualize what goes on inside the heater housing, you can probably find good diagrams on google image search.

This looks close....





I can't find a good diagram of the insides of an actual Honda heater system, so maybe you can use this one from a Ranger to give a generic idea of how a typical door system works. (Ignore the top half of the pic)




In my 10 years at this small dealer, I personally have not seen problems with the doors inside the heater housing.

On other Hondas I have seen a few water valves bad though, due to the steel screw rusting and breaking the plastic shaft apart (the screw attaches the arm to the shaft of the valve).

ezone

Another generic diagram

RoccoCroce

That bottom one is really clear.
It kinda supports my theory on air pressure because the output side of the heater core isn't closed off entirely but that doesn't matter.
What're the odds of the blend door being broken?
I'm starting to feel better about all this. I can't wait to get out there. This Claritin has to metabolize asap -_- .
Rocco

ezone

I still don't get how you are using the term 'air pressure'.
Air pressure doesn't move the doors, actuators do.
The doors direct and control air flow.

WAITwaitwait: Air flows from higher pressure zones to lower pressure zones. Is that it?


Well....the water valve only closes off one of the heater core tubes (when it works correctly). The other hose remains open at all times.
Wouldn't that be the same?


If the air inlet side of the heater core is completely blocked, there wouldn't be any air flow through the core at all.
No air flow = no heat exchange to the air.
But the hot heater core can still radiate some heat, thus the water valve to stop the flow of hot antifreeze through the core.

-------------------------------
Beginning with the 2006 Civic the heater water shutoff valve was eliminated, they now rely entirely on the doors in the heater box to shut off air flow through the heater core.
------------------------------


I'll say slim:
"In my 10 years at this small dealer, I personally have not seen problems with the doors inside the heater housing. "


---------------------------

CSB:
I once checked out a Jeep product with a somewhat similar complaint......I guess someone had set stuff on top of the dash and a tube of lipstick apparently went down the defrost vent, wound up inside the heater housing, and was blocking one of the doors from reaching its full movement.
...but I haven't seen that situation on any of the Hondas. Yet.

Food for thought:
Do you have kids that might find the dash vents "fascinating"???




Coincidence??

RoccoCroce

As for the heater core, I meant output of radiant heat, but I'm learning that once the flow is halted by the water valve, the amount is negligible.

I get that the water flow ceases once you shut the valve like an SPST switch (:
I think I was just working myself up over minute details.

I was thinking about air pressure and pockets but after thought was, "Yeah.... that wouldn't matter -_-" So I reject my own theory.

I NOW understand that air must flow over both the heater core and the evaporator.



Okay, now for results.

Turns out, the sheathed cable between the actuator and the water valve is rather lame. It only seems to rotate the water valve about 20-30 degrees and neither full on either direction. Upon disconnection it, I've noticed the cable only travels about half an inch to MAYBE an inch outside of the sheath.
With that aside, manually operating the water valve with the above troubleshoot, I was able to replicate all optimal conditions. Ambient air, heat, AC, all function perfectly when manually actuated.

I took a couple pics to show AS IT WAS, before I dismantled it to move manually.

One is all the way actuated to HOT and the other is all the way actuated with COOL- via the temp ****.

They're attachments, I hope this forum manages attachments well.

If not I'll re-UP into BB code.


....been a very busy day....

As for kids, no.. I did find some interesting things that didn't belong in key areas..

Allergies in southern NJ suck..



~Rocco

ezone

Time to get into the dash side and see why that cable isn't moving far enough.

Is the sheath unclipped from its bracket under the dash?
Does the actuator not have full travel?
Is the linkage obstructed by something?

Could it just need lubed a bit?

One red arrow points to the actuator, it's on the bottom of the heater case and you can usually find it from the passengers front floorboard area.. MAybe let the glovebox open up wide and reach it that way, maybe look under the edges of the dash. Move the temp control and follow the noise

RoccoCroce

With the cable disconnected at the water valve, I should be able to inspect the actuators full travel. I'm going to be looking into it in a little while.

Thanks again!
~Rocco

RoccoCroce

Fixed. SPDT relay fell into the gearing -_-. just ever so barely. Couldn't see it from below. Just jammed my hand up there and searched around. It must've been slowly eating the harness over the past couple months. I relocated that section of harness.
I took pics but I'm going to bed. Too long of a day.
Thanks so much for your help!

ezone

RoccoCroce

That gif is apeshit funny.
It makes me feel better that I still got to learn.
I was under there three times, three different days and I guarantee that if we
Didn't go through all of this, I wouldn't of reached the conclusion sooner.

ezone

Admit it....You thought, "YAAAAAAYY" in Kermits voice.

There are days I feel like I couldn't even fix a sandwich.

RoccoCroce

I'll second that.
At any rate, I greatly appreciate your help.
Really nice of you to hang around and put up with some mild asshattery.