WinstonSmith

I know this question probably seems silly but this is getting annoying: My air conditioning cuts on on when I hit a significant bump in the road. Have any of you had this problem?

4drEF

What kind of car?
What do you exactly mean by 'cuts on'? - just the interior fan, just for a split second, etc?!?!?!?
Right before you started getting this problem, did you or anyone do work on the car? Maybe under the dash, radio install, engine swap, wire tuck, etc?

WinstonSmith

I'm sorry I should said my car type it is a 91 ef civic hatch back. By cuts on I mean I will have the switches set to the on position on my panel and nothing will actually turn on until I hit a bump. I installed a radio about a year ago and I also did some speaker work a few months ago.

4drEF

Was this happening before you did the radio/speakers?
Trying to figure out if this is something new to your car or something that has been there since you got it.

When you push the AC button before you hit a bump, does the blue light come on?
Or does it only come on after you hit a bump?

DCRB

wait are we talking ac like actual air conditioning or as in the blower motor wont work till u hit a bump?

WinstonSmith

It would be the blower motor of the ac. That's what doesn't cut on till I hit a bump. It has never done this in the past.
My ac light stays on.

♡ROXY♡SuRf

I am having the same problem with my 2005 honda accord. Did you ever figure out the problem?

fcm

My guess it the blower motor resistor is no good, if blower motor will not work in any speed it is most likely the blower motor itself.

Try the blower at full speed, if that works replace the blower resistor, if it does not work when set to any speed, turn it on, [any speed and gibe the blower motor a good whack.

If blower motor is not working A/C will also not work, 94

tamboo

reset ecu after replacing. learned that the hard way like a lot of things....

fcm

Why, the ECU has no control of the blower motor. 94

crxaddikt

so, did you ever find out the problem of why your A/C cuts on when you hit a bump ??

back around 2004, i had my 90 CRX si dropped off at a shop called the Honda House, cause my A/C stopped working, and after they spent hours trying to diagnose the problem, they said its a bad ECU, they said the part that controls the A/C in the ECU is burnt or something like that ??, i ended up getting an ECU later but mostly cause i wanted to get an 89 integra ECU so it matched up with my DOHC ZC that i had swapped, but after putting the other ECU i got in, it did'nt make the A/C work or anything?, and i did'nt think it was going to either, since i already read around online about it and asked people, which said "there is no part of the ECU that controls the A/C", so i'm not sure if the mechanic was just bullsh**ting or what?, but it cost like $70 for each hour they diagnosed it i think, and usually i don't take my crx to shops and try to do everything myself, except stuff like A/C, which i have no experience with, they did stuff like put dye in it and looked at it with a black light and checked for leaks, checked all the components and other stuff.

later on my friend whos a mechanic looked at it and it was working except it only worked for a little while and then always blew the fuse for the A/C condensor, and it would work again once you put a new fuse back in until it blew again......, and since then i just stopped using it and have yet to get it fixed so its working properly again, but i mean to do it soon, but luckily i got a second car in august, a used 03 accord which does have nice A/C, cause i had enough of suffering in the texas heat for 12+ years with no A/C in the crx.

~sp33~

There are connections on the ECU for the AC to control the fan in relation to engine temp.

crxaddikt

oh, ok, i mean i did remember hearing someone say there was one thing that it does control from the ECU for the A/C, and that might of been what they said,

but would an A/C still operate and work even if that part of the ECU was broken and did'nt work to tell the fan what to do in relation to whatever the engine temp is ?

but i still think that mechanic was making that up about my ecu being bad, as to why my A/C was'nt working, cause if it was the ecu, then it would of probably worked after i put in that other ecu i got ?, and it did'nt, unless it was a really rare instance where the other ecu i got (it was a used one), just happened to also have the same thing fried or "burnt" on it, which he said was bad and then the A/C would'nt work with either of the ecu's, but i doubt that would happen, but since i've had the other ecu, its worked good and everything, and later on i had my friend Leo, whos a mobile mechanic whos real good, look at it, and he was re-wiring or organizing the wires all around the A/C wire harness and might of tested all the relays and stuff, and the main components are all good luckily, and he actually finally got it so it was blowing cold air, but he did'nt finish fixing it, that was one day, and i paid him $100 to get that far, and was going to have him ffinish another time, and he said its not much left to do, and i think the thing he said needed fixing was something to do with how the A/C cuts off and on during idle, not sure exactly, but that was i think 2011 and i just have'nt got on him to get him to work on finishing the rest so its all working, and a couple years went by, he is busy alot of the time and kind of hard to get him to come out and stuff, but it was really me, for just not getting on him to do it though.

anyway, at least i now know what the ECU does to control the A/C, so thanks for letting me know that bit of info.

fcm

"It would be the blower motor" Again the ECU has nothing to do with the blower motor, condenser fan yes, blower motor no. 94

~sp33~

The likelyhood that both ECU's were bad is pretty low.

The ECU also links the AC switch on the dash to the compressor, so it is possible that a fried circuit would prevent the AC from switching on.

fcm

"The ECU also links the AC switch on the dash to the condenser" say what???

How is the ECU "linked" to the condenser? 94

4drEF

I think he meant the A/C condensor FAN, but that still doesn't make sense.

For the A/C system, the ECU receives a ground and provides a ground.

The ground starts through through the blower speed switch. You can not have the blower fan set to OFF.
When you press the A/C switch on the dash, the ground passes through the A/C thermostat and then through the Pressure Switch (for safety checks). If those are both good, the ground makes it's way to two places.
One path goes to the fan relay for the A/C fan (under the hood) to turn it on.
The other path goes -TO- the ECU.

This ground -TO- the ECU does 2 things.
The ECU senses the ground input and bumps up the RPM a little during idle to compensate for the extra load of the the A/C compressor.

It also triggers a ground to put the A/C compressor clutch into operation. - this is the -FROM- ECU ground.

~sp33~

Edited, meant to say compressor.

Someone's been studying their wiring diagrams

crxaddikt

well whatever happened to the original guy who made this post ?, WinstonSmith ?, maybe he fixed the problem already ? or just does'nt care anymore ?, and i am not one to hijack a post or anything, so i just don't want to appear that way, but if you notice the first thing i said at the top was asking a question to the post creator, asking him if he ever got his problem fixed or not ?, so really thats what i first typed, but then i started going off in detail about problems i've had that are somewhat similar, but i did'nt mean to switch it so people would be helping me instead of him?, just wanted to point that out, but i do still own the crx i'm talking about and the A/C still has a problem where it does'nt work fully, but luckily i finally got another second vehicle in august 2015, a used 03 accord, which has good cold A/C, so i'm not suffering or anything right now, and so i got time to be able to figure out and fix the crx A/C, but i still do want it fixed and working again for when i do use it, so it does help for me to learn about these things i did'nt know about which some of you talked about, on how the whole A/C system works and how its linked to the ECU and everything, and thats good to know, cause it might lead me to pinpoint what my problem is.

~sp33~

The post is from 2012, the car has probably been crushed into a cube by now, and the OP has probably moved on to a car that's more reliable.

fcm

Maybe cubed, but it would already be another car, [or tin can] by now. 94