kirks_works

First this is not my car but I'm helping a friend with it, so I will try to explain the best I can second hand.

Ac does not blow cold, low pressure side reads 100psi, the condenser fan does not turn on, the compressor clutch will not engage and possibly the radiator fan will not come on either but the car never over heats. No check engine or maintance lights to help either. She was told by a mechanic that the "computer" was causing the probs and he could fix it. Idk about the "computer" causing the prob but I checked all the fuses and suppect it could be a relay. Any help is greatly appreciate, thanks in advance.

kirks_works

Took the car to thed Honda dealer and they told her she needed an under hood fusebox.

civichb20

they would know how to fix it ac can be hard to work on especially if you do not have the right equipement good luck.

kirks_works

Well yesterday I took the under hood fuse box completely apart and checked every piece for continuity. I checked every fuse and relay along with all of the connections they make and the bus bars in the three layers of the box. The fuse box checks %100 good. Idk why they would tell her that it was bad, she paid for the diagnosis ($95) sounds like they don't know or they wanted to make some quick cash.

Dr.g

That fuse relay box aka the MICU has many functions, not just a fuse box and unless you have testing equipment for checking I dont think that simple continuity checks will give you the whole story. So if you paid to have the dealer diag it and they said the unit is bad put one in. The problem with you takeing it to the dealer to check the a/c then takeing it home to fix it is the dealer will stand behind their diag and if the fuse box didnt fix it you could hold them to their incorrect diag then not pay for their mistake. Now its in your hands, good luck.

skracer13

I don't know how good your are with electricity, but you can check each components. Fan relay, condenser relay, compressor. On a relay you will have (12+ #1)12+ capable of high current going into your relay (if the fuse is good) that will eventually supply power to your component. on that same relay you will also have another contact with ground to it and the adjacent contact will also be a (12+ #2)12+ lower current coming from a switch that is used to energized the coil in the relay in to allow 12+ #1 to have a path to the component. Ok now that we understand how the relay work, you can jump 12+ #1 directly to the output without energizing the coil and your component should turn on. Keep in mind that is is only to test your components, if a your components come on then your problem lies in the input voltage and/or ground.

Dr.g

Ya start jumping power to contacts.... do you know a good towing company?

skracer13

The information I have provided is only for troubleshooting purposes, if not mechanically inclined, disregard my information because improper procedures risk the chance of damage to other electrical components.

kirks_works

I just checked the cabin fuse box eveything tests ok. The only thing i can't test is the circut board. After talking to the dealer again they tell me its the cabin fuse box and parts + labor = $750. They said they would sell me the part for $330 (no warranty and if its not the prob... too bad because I took it out of the box). I am mechanicaly and electricly inclined. I have no probs with checking fuses, relays, capacitors, transistors and resistors.

skracer13

I would recommend finding a use under dash fuse box from a salvage yard locally or online. Should run less than $100 bucks. Reason I would have to agree with the dealer's diagnosis is because that under dash fuse box contain the Multiplex Control Unit integrated with the whole assembly. I have seen a couple units becoming bad from electrical spike/surge, heck even a couple of ECM. For some reason honda's vehicles 2001-current is more electrically sensitive. If you still want to pursue a fix without replacing the UDFB by rewire the AC system, PM me and I will assist in any way possible e.g. wiring diagram...

nobuyasu

I have the same problem with my 2005 Honda Pilot. The AC was working great, then one day it stopped working. I then noticed the AC compressor goes not engage. I took it to the dealer and they indicated they found a leak in the condenser. It will cost about $783 to change the condenser, replace a couple O-Ring seals, and recharge they system R134A. So of course I questioned this as I was wondering how a leak in the AC system would prevent the compressor from engaging.

After some internet research, I found that several Honda models (CRV, Pilot, Odyssey, etc) have a problem where a rock or road debris will hit the condenser and cause a leak. If the AC system losses it charge, the AC pressure switch will disable the AC from kicking on...meaning the compressor will not engage. There can also be another problem. The AC transistor is also known to fail (https://honda-tech.com/forums/honda-civic-2001-2005-78/diy-how-fix-ac-power-transistor-2041582/).

Now I'm debating whether to pay the $$$ to have it fixed or do the repair myself.

Anyhow, I hope my information help as it seems you were givedna different direction...the fuse box.

skracer13

Yes the system will not operate if system pressure is low nor will it operate at an high pressure, If your compressor temperature is excessive, the thermal overload on the compressor will kick in as well. I'm pretty sure kirks dont have a leak because as mention 100psi on low side. system pressure levels out (high=low side) when system is inactive.

kirks_works

I have plenty of pressure so I feel that I can rule that out. I have also turned the ac on a jumped the pressure switch and nothing happened.. If it wasn't so hard to get to the compressor I would test for power, but I can't get to it. I have looked in several local salvage yards no luck yet. Thanks for the help tho.

kommando

I am having a similar issue but not sure if the solution will be same, this is what I have tried so far

AC 's not working, thought it was just low pressure so when fitting gauge to low pressure side found pressure was in fact high at 70 psi.

2002 2.0L UK manual car

Both fans are not coming on when AC is switched on and clutch not operating

Fuses all check out ok and none were blown, 1 and 4 in engine bay and 14 inside

Have voltage to AC pressure switch (though it did seem to vary but check sheet said 5V is enough and it stayed above 5V) and the earth path showed good route

All relays work when put into horn relay position, both radiator and condenser relays plus compressor clutch relay

All relay sockets show battery voltage at position 3 and at 1

When jumper used between 1 and 2 fans do not come on and cannot hear a click from clutch

Compressor and both fans spin freely when turned by hand

Have checked feed plug to compressor fan and get 12V plus route good to earth.

Tomorrow will try feeding 12V direct to compressor fan and also checking rad fan and compressor clutch.

Also found a post saying on a GEN1 CRV both fans failed simultanously so that is a possibility.

kommando

Condenser fan motor is dud, confirmed feed and good earth to Rad fan so next need to do direct feed to that motor, access to compressor clutch is difficult but need to check that too.


Question, if the rad and condesor fans are dud will this lock out the compressor until the fans work ?

kommando

Direct feed to the rad fan shows that is dud too, ordering both fan motors and will get to compressor when I drain the coolant and take the rad out to fit the fans. Tested the route from fusebox relay socket to earth and it shows no route, so wire to compressor is shot or the thermal switch is fused on or the field coil for the compressor clutch is blown.

Duane_in_Japan

Sorry I dont remember the name and your vehicle may not have one of these on the fuse box, if it does then maybe its not available seperately, hence the purchase of a full fuse box.

On older Hondas, there is a box that plugs into the fuse box, it controls several items such as AC (?) and wiper speed (intermittent) and other accessories. I would take a very close look at the fuse box and see if it may have one of these items plugged into it, of course its much bigger than a relay, maybe get a fuse box from a recycler. You also must have another location to hot wire the compressor than down near the compressor.

OK, I just found it in my tool box from a Honda Vigor (CB5) in Japan, its an ICU, not Ignition but something Control Unit, Part # 386OD-SL4-003 I think. Its about 2 inches by 3 inches by 1 inch thick. It plugs into the fuse box and then a wire harness plugs into the ICU.

b2ride

help someone please tell me what ECM stands for..97 honda,,thks b2ride@yahoo.com

Duane_in_Japan

ECM, Engine Control Module, the main computer. Also called ECU (Unit), TCM for the transmission, newer vehicles, PCM, Powertrain Control Module for engine and tranny.

ICM from above, Integrated Control Module, controls all kinds of things on the cabin fuse box.

Testing with only a multimeter, volts and ohms is only a base line test, you have to do a voltage drop test at connectors, junctions, grounds, plugs. Then you need to use an amp meter to see how much power an item is pulling but that needs much more experience, might as well brake out the oscilloscope and Amp Clamp. Bypassing items is ok but like mentioned, you need a full understanding and a wire diagram does not hurt either.

kommando

Mines now fixed, both fan motors had failed and the clutch coil on the compressor too.