A/c Quit Working, Confused...

[jeffcoslacker]

The big thing is, if you have a cold sweaty low pressure line going into the firewall, and a hot return, the system is working right, so you are left with a flooded core, heat contamination from a control valve problem, etc.

Sorry I keep asking so many uestions, but this is interesting to me, for some reason.

Did the air stop working suddenly, like something broke, or just slowly crap out?

Is the air blowing from the vents sufficient? It's blowing strong, just not cold, right?

Are both fans on the radiator running when the a/c clutch is engaged?

Is the a/c clutch engaging?

[funky]

again, where is the heater valve and how do i determine its position? what is wierd is that the A/C was really cold a few days ago. doesn't seem like a leak...

[jeffcoslacker]

I'm not familiar enough with your car to tell you exactly, but in general it will be in one of the coolant hoses going into the firewall, generally has a vacuum line or cable going to it, and you can see the mechanism changing position on some of them as you change from heat to cool. If you can't locate it, another check is just to see if one heater hose is signifigantly warmer than the other when the motor has been running for a few minutes. The valve shuts off coolant flow to the heater core, and the return hose should be cool (no circulation) when the heater control valve is closed. The supply side will be the same temp as the radiator hose, more or less.

[funky]

Originally Posted by jeffcoslacker

The big thing is, if you have a cold sweaty low pressure line going into the firewall, and a hot return, the system is working right, so you are left with a flooded core, heat contamination from a control valve problem, etc.

Sorry I keep asking so many uestions, but this is interesting to me, for some reason.

Did the air stop working suddenly, like something broke, or just slowly crap out?

Is the air blowing from the vents sufficient? It's blowing strong, just not cold, right?

Are both fans on the radiator running when the a/c clutch is engaged?

Is the a/c clutch engaging?

yes, the a/c was working yesterday, this morning it was slightly cool, and by the end of the day it was hot. you could actually turn the heater knob and it would get hotter, but the cold wasn't cold, it was definitely hot.

air is blowing strong. just not cold anymore.

the engine rpms go down when i turn on the a/c, so i'm assuming the clutch is engaging. 3 days ago i had my honda's idle rpm adjusted a bit higher, because the engine would shake when the a/c went on (because the rpms would drop too low -- this happened over a longer period of time, but got so bad that we upped the rpms to fix this).

another problem i had that i haven't fixed was that the 2nd fan wouldn't come on unless i had the a/c on. sitting at idle, the car would overheat if the a/c wasn't turned on. i think i was told it was the cooling sensor or relay switch.

[jeffcoslacker]

Do both fans run with the A/C on, though?

The secondary fan will only run when the A/C is on, that's normal. but you shouldn't overheat unless the primary fan isn't working at idle. If it isn't, then there is a problem with the relay or sensor, yes.

[funky]

well, i haven't watched the fans yet. i notice the temp gauge goes up after at idle and engine has been running hard like on a highway. soon as i turn on the a/c (and the a/c button must be on, not just the "fan"), the temp gauge shows the engine temp coming back down to "normal". only thing i could think of would be one of the fans doesn't come on like it should unless i have the a/c on. maybe i'm wrong. but that seems like a totally different problem, no?

[jeffcoslacker]

OK. We gotta find out if the low pressure side line is getting cold, the heater valve is shut, and both fans working with A/C on.

I believe on yours the primary fan is the passenger's side, and the aux fan is the other one.

You are right, it sounds like the compressor is working.

It may be that the A/C system itself developed a blockage. That would cause both the loss of cooling, the increasing load from the A/C on your idle, but then it shouldn't be producing sweat from the core drain.

Man, I love a good mystery. Let me know more tomorrow.

It wasn't retrofitted to use 134A refrigerant when all that work was done, was it?

[jeffcoslacker]

Originally Posted by funky

well, i haven't watched the fans yet. i notice the temp gauge goes up after at idle and engine has been running hard like on a highway. soon as i turn on the a/c (and the a/c button must be on, not just the "fan"), the temp gauge shows the engine temp coming back down to "normal". only thing i could think of would be one of the fans doesn't come on like it should unless i have the a/c on. maybe i'm wrong. but that seems like a totally different problem, no?

Yes and no, depends how high the temp goes as you sit. My own car will go as far as 2/3 or more up thje gauge before the primary fan comes on in hot weather, that's normal for it. If the A/C is on (both fans running) it sits rock-steady at 1/3 no matter what the conditions. So you will see cycling of temp with the a/c off, because the primary fan only runs on demand, and the temp has to reach a set point before it kicks on, then the temp should slowly return to it's previous level.

[funky]

i don't think 94 honda accords had r-12. ok, i will check the fans tomorrow. i don't know if i will be able to find the low pressure side line or the heater valve. i couldn't even find the sight today...man do i need a friend who knows engines

[jeffcoslacker]

OK, I forgot yours was that new. General layout of an a/c system:

Compressor (you know where that is)

1 line out to the receiver (big aluminum round can) and on to the evaporator core (goes into the firewall)

1 line out of the firewall to the condenser (in front of the radiator)

1 line from the condensor back to the compressor

Low pressure (cold) side hoses and lines are generally bigger.

Everyhing from the compressor to the firewall should be cold and sweating with the system on. Everything from the firewall back to the compressor (condensor side, high pressure) will be hot, (very)



If not, something is wrong.

[mpumas]

The heater control valve is located in the engine compartment on the passenger side firewall. A wire is attached to the valve which goes to the heater control knob on the heater control panel. When you turn the knob you should see the valve move. If it doesn't move, it may have become disconnected on the heater panel. Or maybe the heater valve is leaking. You can manually move the lever on the valve to open or close it.

[funky]

Originally Posted by mpumas

The heater control valve is located in the engine compartment on the passenger side firewall. A wire is attached to the valve which goes to the heater control knob on the heater control panel. When you turn the knob you should see the valve move. If it doesn't move, it may have become disconnected on the heater panel. Or maybe the heater valve is leaking. You can manually move the lever on the valve to open or close it.

come to think of it, i have moved the heater knob (i think i said this in a post earlier), and the temp did change from hot to hotter. so i think it is working (maybe not all the way though?)

i'll see what i can see

[funky]

and i have had problems with the heater valve in the past...maybe this is it again?

[jeffcoslacker]

OK, assuming the car has been sitting all night, if the heater is mixing with your A/C air, the a/c should work fine until the car starts to warm up. Cold motor=no heat, so the air should be cold and get warmer as the engine warms up.

[jeffcoslacker]

Gotta see if the A/C clutch is engaging. Don't know how familiar you are with the compressor, but here's the scoop. The clutch on the face of the a/c comp pulley sits unmoving until the comp engages, then it turns with the pulley. It should engage, and stay engaged. Short cycling (clutching in and out rapidly) indicates refrigerant loss.

Both fans should come one when the clutch engages, or else there is some concern there.

Within a few seconds of engagement, you should be able to see a cold line move down the low pressure line coming from the compressor out to the interior of the car (sweat or frost).