Wankenstein

Previous related thread: https://www.civicforums.com/forums/3...questions.html is long winded so decided to start new. Summary of above thread is...possibilities of why this newer (1 year old, other than used condensor) a/c isn't blowing as cold as it should:

1) Heater valve: working correctly
2) Blend door: working correctly
3) Freon level: has correct level
4) Compressor clutch air gap: engages properly
5) Evporator partially clogged/dirty: haven't checked yet
6) AC thermostat: OEM unavailable nationwide discontinued part
7) Darker window tint: coming soon
8) Contaminated system/weak compressor
9) Climate control solder joints: reflowed solder joints..working correctly

Pretty hot ambient temps and high humidity lately here in mid-west coast of Florida and a/c is again not blowing cold as it was during cooler ambient temps a month ago. I haven't put a digital thermometer in vents recently but, I can feel it's not close to the 42 degrees is was putting out a month ago. Recent day time ambient temps have been in the mid to high 80's, humidity near 100. Air (a/c) blowing on my face and body feels around 80 degrees during daytime driving.

However, at night or in parking garages (days) the a/c system feels much cooler. I'm sure the 30/rear and 50/front tint I plan to have installed soon will help the AC system cool better but, doubtful it will solve the issue entirely. I'm leaning towards the AC thermostat and/or dirty evap core.
What exactly does the AC thermostat do and if it's not functioning properly can it cause the discrepancy in the AC systems ability to cool in relation to ambient temps?

Wankenstein

Reading through similar threads I found this: http://www.hondacivicforum.com/forum...ue-help-69366/ Should I try bypassing the AC thermostat?

ezone

AC thermostat is responsible for monitoring the temperature of the evaporator core, then cycling the compressor on and off to maintain evap core temp within a certain range. ALL it does it turn the compressor on and off based on core temp. .

Does the compressor cycle on and off at regular intervals on a mild day? I remember you thought it did as evidenced by the feeling and the dash vent temp going up and down by about 5 degrees at regular intervals.

Does it do the same (cycle) on a miserable hot day? (it may not be able to due to heat load)

Did you ever take temperature readings from the suction pipe as it exits the firewall, on a hot day with the system running full blast?

Recirculate flap is closed on a miserable humid day? (does it actually work?)


Bypassing the ac thermostat would only keep the compressor running all the time, and if it already never cycles off on a hot day then bypassing that control isn't going to serve any purpose.
If you left it bypassed (comp runs all the time the system is turned on) then the evap core will freeze into an iceberg on a mild day.

Wankenstein

Thanks.

During cooler ambient temps (50's-60's) last month it seemed to. It was in the paint shop for past two weeks and I just got it back it yesterday morning. I didn't spend time watching and listening for compressor cycles today or yesterday although, at stop lights it didn't seem to be cycling on/off as often as it should. I pressed the a/c (green light) button a few times occasionally at stop lights to ensure compressor engaged and it did every time.

Today was a hot/humid day. I couldn't hear compressor while driving so not sure if it was cycling properly. My guess is that it's not. I just got back from a drive a while ago (late evening) and ambient temps is 77 degrees, windy and low humidity. Unfortunately, again the a/c did not get cold.

I took a reading on cool day last month and it was in low 30's.
Haven't tried a reading on hot day on full blast yet. I work a double tomorrow so I will use my IR thermometer on it Wednesday.

Last month with glove box door removed I could see the actuator arm shut the recirculate flap. I haven't pulled the cowl off for a better look to see if it is closing fully.

Okay. Being that the car is 22 years, no filter and most likely still has the stock evap core..what effect would a dirty or partially clogged evap core have on the system?

Wankenstein

Searching related threads and found this: http://honda-tech.com/forums/honda-c...nough-1593321/

Reply 7:
(copied and pasted) "Where is the high side pressure at? This is basically the amount of charge you have. Also, 92-95 civics have a problem with the ecu relating to a/c. (trust me on this one, I just recently had one for five days and had to figure this out. On top of that, my hand got wrapped up in the belt while it was running and my thumb got cut off) sewn back on now though. Anyway, the compressor stays on all the time no matter what. So, with the car running, and the switch off, the clutch is engaged while the condenser fan is off, causing the freon to overheat and spike the high side. When this happens, the compressor will sometimes "purge" freon out through the high pressure relief valve, causing a low amount of freon, causing coolish a/c.

So, see where your high side reading is at and make sure the compressor cycles properly. It needs to cycle so the freon isn't constantly moving. It needs to be held in the evaporator so the freon has time to cool off in the condenser and return back to its liquid state.

Vapor freon = not cold
Liquid freon = cold"

ezone

There is no "should", it will keep the compressor ON until the core temp reaches the turn-off temp. On a hot day (plus an old inefficient system) the core may never get cold enough to cycle the compressor off.

At 77 deg that's not hot at all, so it should have been able to cool well if the compressor was running. (clutch engaged)

First notice is likely less air flow volume due to blockage or restriction.

The air that is able to pass though the core may have plenty of time to condense its humidity and shed heat , but the volume may be low enough that it still seems quite weak by the time you get to feel it as it exits the vents.


I thought you said someone put an expansion valve in this car already? Someone had to take the evap housing apart to do that, I'd hope the core would have been cleaned at that time.


This is the same scenario that happens when a bad clutch relay gets stuck on. You haven't indicated you have such an issue nor given me anything to be suspicious of.
You should be able to see that your compressor clutch is disengaged when the HVAC is not on.


Not quite correct.... if one understands AC theory.

Wankenstein

Today outside temp 75, humidity 86. During ride to work this morning (before sunrise) I could hear compressor cycle on and off at stop lights. Temp with AC on max cold + recirculate, was barely below ambient temp. I'm starting to suspect a slow leak, air in sytem and the possibility of low charge.

Three months ago purchased car and the "not cold enough symptom" lasted from day of purchase until I took the car to a mechanic roughly three weeks after purchase. The mechanic did a vac and re-fill and afterwards and the a/c worked well (daily colder ambient temps) until three weeks ago... in which during a one hour drive on a hot, humid day the system struggled to cool the cabin and has continued until now.

I have rechecked the heater valve position and heater hose inlet (between heater valve and firewall) by hand and it seems to be working properly. I will recheck recirculation flap. Also, I intend to inspect the evap core tomorrow. Air flow during each fan position seems to very good respectively. My car's compressor does turn on and off with ac button selection (off/on)..so, that part is not related to the thread I linked.

The seller said (a couple months ago) he replaced the expansion valve but, didn't mention cleaning the core. He said he did not replace the core. Seems like he would have cleaned the core unless he either forgot or didn't think do it. I will ask him again.

My friend just referred me to a mechanic that he says is very good. I intend to spend time with it tomorrow to inspect it
before I bring it to the mechanic on a future date.
1) evap core
2) recirc flap movement,
3) heater valve and hose (again)
4) a/c pipe temps, vent temps.
5) compressor cycle times
6) condensor fan

If need be..I may ask the mechanic if he'd be willing to evacuate the system and I will remove the evap core, replace it with a new one and bring it back for re-fill. I'm finding out over the past few years and varying a/c issues that there is differences among mechanics that have a/c system knowledge and extensive a/c system knowledge regardless of how many cerifications posted on their walls. Thankfully, with your help and experience I can try and narrow down the problem for the next mechanic I bring it to.

ezone

Shoulda grabbed the suction pipe to evaluate temperature.
If the comp was cycling then the core should have been close to freezing, feeling the temp of the suction pipe should confirm the temp of the core and cycling theory.

If the core is cold (verified by suction pipe temp) then the system is probably working, but why then isn't cold air reaching the vents?

What if.....the evap housing is missing the seal around the core? IIRC there may be a styrofoam-like core support in the plastic housing that serves to seal the outer perimeter (edge) of the core....or it may be a layer of foam padding stuck all the way around it....At any rate no matter which method was used, this sealing forces all of the air to pass through the core instead of bypassing around the edges....what if that had been boogered when the previous owner had it apart?

Also the foam padding that helps seal between sections of housings (fan to evap, evap to heater)


This thread has pics of a 6th gen core and you can see a layer of whitish styrofoam surrounding the core within the housing


Ya think?

The world is full of people who work on cars. Look around, they are everywhere.
Far fewer can actually fix them on purpose.

Many people in the field are good at replacing parts. Not many are good at diagnosing accurately, and *FFS* electrical is like "the final frontier" of car repair.

Many shops WANT the mechanic who can only fire the parts cannon....because that guy generates far more revenue than the guy who fixes the car by replacing ONE bad part.

The guy who fires the parts cannon looks like the winner to the bean counters,.....but the bean counters only see the first column of beans.
Would be a lot easier if I could just check it over in person LOL. It's tough to teach experience.

Before you try to dictate the process, why not just ask the guy why your system isn't cooling worth a crap on a hot day?

==============

Just read a post on a mechanic group that went something like this (C&P):

A) No matter what shop your in and what group of guys you have there's always that one guy who starts his a/c diag with an evac recharge.

B) can confirm. Guy didn't even check to see if the compressor clutch was working, just hooked up and went for it.

C) Yep....and they end up with a come back

Probably 3/4 of the AC complaints I deal with have nothing to do with the amount of refrigerant in the system.

Wankenstein

I get off work soon and will try it when I get home.

It sure seemed to last month when vent temps were reading 42 degrees with a digtal thermometer and 36 degress with IR gun pointed into vents and suction pipe.. Of course ambient temps and humidity was much lower last month when I checked vents.

Possible and wouldn't be surprised. I saw that foam piece in a video about 6th gen evap core replacement.

Thanks for the link

Sounds good..will do.

I would imagine. Easy for a novice (like me) to think that way and especially the way auto parts store pimp that DIY refrig stuff w/ single gauge.

Wankenstein

Got home and let it idle for around 10 minutes...max cold, fan on high, recirculation mode. The compressor engaged as soon as I turned on the a/c system and the compressor never cycled off.

I couldn't get a good IR reading on suction pipe but it was very cold to the touch. However, air vents read 70 degrees. I disconnected heater valve cable and manually moved the heater valve arm towards the engine (parallel to heater hose) and though it was farther past than the position shown in service manual it effected the vent temps in a positive way. Afterwards temps dropped to low 50's. My guess is the seller purchased an aftermarket heater (ball) valve and even in it's optimal closed position it still allows coolant to pass.

ezone

So sounds like the AC is still working,

but water flow through the heater core is not being completely shut off.

Screw the manual. Make the valve shut off the water flow 100% and lock the cable housing down so that's the new 'full cold' flow completely shut off position.

Wankenstein

I guess part of my confusion is that I'm expecting the compressor to cycle on/off at repetitive intervals and not vary. Thinking that way however, does not factor in changes in ambient temps and humidity that effects efficiency. I'm currently reading this to get a better understanding: https://www.ericthecarguy.com/faq/so...g-with-your-ac

Blasphemy..LOL

The problem is the cable is not long enough to put it/keep it in the new full cold position. I could keep the cable disconnected and zip tie the arm in full closed position until winter. I might be able to find a company that sells customized lengths of cable or possibly use pedal bike brake/shifter cable and size it to fit.

I texted my friend to get the mechanic's phone number and will call him soon. I should be able to get a good gauge on him via phone conversation.

P.S. I just had a thought (which doesn't occur much..lol) Can I set the ball valve in optimal closed position (parallel with heater hose) and then loosen the heater valve arm screw and move the arm to match the farthest point the cable can extend to? I realize by doing this it will not allow the valve to return to max heat but, that's okay for now. It should allow enough coolant through to blend air if needed.

Wankenstein

This morning (ambient temp 75/humidity 85) I removed the cable and adjusted heater valve to optimal closed position then loosened screw and set arm to match fully extended cable position. Air blowing very cold soon after starting engine. I drove it for a while with driver window down and could hear compressor cycling on/off. Blew cold for the entire drive.

My IR scanner seems to be faulty and I intend to return it. Will use digital thermometer to monitor during day/evening/ night.

ezone

Check the end of the cable where it's mounted to the heater box and linkages. Maybe you can gain some more adjustment room in the engine compartment by changing the mounting of the sheath in the dash..

Wankenstein

I tried that a month ago no extra slack. So far I've driven around 4-4:30p and tonight to work and air is still blowing cold.

I'm going to try and adjust the heater valve on the '97 EX I gave my son. It's never blown as cold as it should have and I'm curious if adjusting it to the position I just set my car's to will help it.

I've read a couple other posts on various sites of people adjusting the heater valve arm past the position shown in the service manual and they stated it blew colder afterwards.

ezone

Sometimes things just don't go according to the book and you have to chuck it out the window and improvise.


Is it really faulty, or are you discovering some of the many limitations of IR?

Wankenstein

There's a word for that: LIFE

The IR beam no longer comes on, it now only reads in celsius and it's erratic.

Some (not much) of the a/c pipe is exposed..should I wrap foam around it?
Any benefit to heat wrapping headers or heat shield to lessen heat near the condenser and a/c pipes?

ezone

I'm not sure there would be much in the way of tangible benefit.
Wrapping exhaust might lead to premature rustout, I've heard the wrap holds moisture..

Wankenstein

Thanks. Also, thanks for all the related replies. I'm not calling this solved yet until after a few weeks of driving in hotter ambient temps but, I'm very optimistic at this point. Hoping to get it tinted within the next couple of weeks