Erocer

I really could use some help with this I have a 1996 Civic DX I live in Houston just gets ridiculously hot.
It started with something simple it was popping fuses on fan condenser.
Was thinking to myself the car is 20 years old might as well go-ahead rebuilding replace and do the whole thing.
I got a new condenser new compressor new evaporator new dryer new expansion valve pressure sensor switch from Honda made in Japan.
Cleaned out all the lines with pure or 99.9% alcohol electronic grade and pulled a very long vacuum around 12 hours. around
Even pulled all the ductwork out cleaned everything and put new foam all way around.
Was reading the manual so I pulled out the clutch relay and bridged it it put in about 18 ounces of of Freon put it to low-pressure to about 45 pounds pressure to about 175 pounds high side.
and was all happy with myself put it all back together
my clutch will not engage and the condenser fan will not turn on.
picked up a used fuse box with extra heavy duty relays and even put a whole new computer in their and still nothing same thing.
completely and totally frustrated and start to warm up your I need some help

mk378

Make sure evaporator temperature sensor is plugged in. If the sensor is open, it will think the evaporator is very cold already and not engage.

Trace the control signal through the wiring. Realize that the system uses negative logic, that is the HVAC control panel pulls the wire to ground when the A/C is to engage. This then passes through the pressure switch to the ECU. The ECU is in the path so it can check the engine rpm and open the IACV with a slight delay to prevent stumbling or stalling when the compressor engages. When the ECU has a (ground) signal from the control panel and pressure switch and decides it is OK to engage compressor, it pulls the relay coil to ground.

Former User

Test fuses 17 and 56.

https://honda-tech.com/honda-civic-d...fuses-3079359/

Erocer

definitely go by the schematic and double check everything I know the temperature sensor is plugged in but I said before I pulled the entire ducting system underneath the dash out put a new evaporator coil and expansion valve and when I did that I double checked and cleaned the temperature sensor there's really not much to that thing is a thermocouple/diode.
I must wait for the rain to stop I'm in Houston been raining here allot.
Now here's something strange for you to ponder when I had the bridge on the AC clutch bypassing the relay I revved up the engine just a little bit and the wire I was using as a bridge got super hot if I would not have pulled it it would've cooked everything.
it was definitely pulling way to many amps maybe the ground is not on your properly or or I have a direct short ?

mk378

The clutch uses about 5 amps. Small wires will get hot. There is no need to jump the relay for charging or for testing. If you jump the compressor on but the condenser fan is not running, the high side will rise out of control and it is easy to pop the relief valve or even blow a hose.

Former User

Start with the basics. Have you tested fuses 17 and 56?

Erocer

I've been working on cars since 1977 and I was just trying to keep up with the manual about bridging a relay.
the first time I charged it the condenser fan was running but the high low pressure switch was no good I have to stop buying them from AutoZone that's why I went to Honda to actually get that pressure switch I've been having quite a failure rate what AutoZone relays and pressure switches and such

mk378

With the system charged (and summer temperatures) the pressure switch should be closed all the time, even if the compressor is not running. So you can check that with an ohmmeter, just unplug the switch and confirm it is closed.

Notice from the schematic though that even if the pressure switch were bad, the condenser fan would still run when you press the A/C button. Because it is connected to the line before the pressure switch and ECU.

Former User

Problem fixed now? If not, did you check those two fuses?

Erocer

Unfortunately no
Fuse 47,42, 56 getting 14.2volts at the compressor and condenser fan relays 1 3 + 1 + 3 again 14.2volts at the high low pressure switch one side I'm getting 8 volts on the other side 4.6 volts. At the thermostat no voltage anywhere. Was up late last night working I have to go install this part today and when I be back and try to pull the rest of my dash apart to get to the fan and heater switches and the heater controls. I can tell you when I turn on the I see A/C light does come on recirculation light does come on the recirculation vent open and close and the fan does turn on.
I have been going to this website and others trying to find the location of a diode I have a DX model I cannot find it anywhere it says it's by the kick plate it's not there

Former User

Fuses 17 and 56 are the only fuses relevant to your problem.

Voltage test both:

https://honda-tech.com/honda-civic-d...fuses-3079359/

mk378

You really need 12 volts on the blk/yel wire at the thermostat. If fuse 17 is good maybe you forgot to plug something back in after R&R the evaporator box.

fcm

You used alcohol to flush the system???

Alcohol is a hydrocarbon, and is a contaminate. get some A/C flush and do it again.

Are you sure you jumped the correct terminals in the relay plug? 94

Erocer

First I'd like to thank you for getting back with me so quickly .
Checked fuse #47 it's good. I pulled the fan blower motor switch/ resistor and I believe it's good I'm not sure how to test it I pulled it apart cleaned all the contacts with a Dremel and my copper wire brush. What did over the one AC engaged well at least the light came on I got all 1 2 3 and 4 fan speeds going. I pulled the clutch and condenser relays back out and they are grounding and I ran it to see if it was coming out earplugs in at the clutch and at the fan motor and yes I'm getting continuity so the wires a good there. I'm really not sure what else to test but like I said there is no power going to the thermostat that's attached to the evaporator coil no power in either of the 3 Lines going in

Erocer

Former User

Due to vast knowledge, you ignore requests for information and advice. If you ever decide to create another thread, please read the forum Rules sticky.

Locked.