AC Suddenly Stopped - Pressure/Fuses/Relays/Switches Fine

[RonD]

Look in the engine bay where the black vacuum line goes into the cab, there will be a second vacuum line with it, usually Grey color, follow it
If its not plugged in then plug it, that vacuum line is only used with MAX AC, so if its open you would lose what little vacuum you have in the cab

It was used to cut off coolant flow into the cab, operated a by-pass valve on the heater hoses

 

[Spidey300]

Look in the engine bay where the black vacuum line goes into the cab, there will be a second vacuum line with it, usually Grey color, follow it
If its not plugged in then plug it, that vacuum line is only used with MAX AC, so if its open you would lose what little vacuum you have in the cab

It was used to cut off coolant flow into the cab, operated a by-pass valve on the heater hoses

That seems connected. I can trace it from the 4 way valve on the heater hoses to under the blower motor. Cant actually see where it connects but it doesnt feel loose. Under glove box inside I see the connector where it comes in and connects to some kind of door lifter then the other multicolor line harness on the left side behind the glove box.

What about that valve with the broken end in my pic? It's on driver side of the engine.

 

[RonD]

Look at the vacuum diagram on the rad support top plate, should be color coded

The valve/door under the glove box, white vacuum line, is "T'ed" to the grey one
That valve/door closes off Fresh Air intake, so fan pulls air from inside the cab, vs HOT outside air
In MAX AC that door is closed so AC will be re-cooling already cooled air from inside the cab, vs hotter outside air
Its "T'ed" to grey line because shutting off coolant flow thru heater core also aids cab cooling

 

[RobbieD]

. . . but fixing that wont help if the AC still cuts to hot defrost with WOT . . .

The compressor is supposed to cut off at WOT, by design, to free up engine power.

 

[Spidey300]

The compressor is supposed to cut off at WOT, by design, to free up engine power.

Right, but not start blasting hot air out the defrost vents, right. From everything I've read, that means I'm losing vacuum.

No one has a 2.5L that knows how that 3-way vacuum fitting is supposed to connect to? I found some other ppls pics and it looked like their yellow line from evap went straight over to meet the other lines at the intake. I swapped mine to do this but it didnt make a difference.

I have the glove box flopped down so I can see that max ac door. It doesnt move when I turn to max ac. In regular AC, the dash vents work (just hot) but when I switch to Max, it switches to the defrost.

Anyway, thanks guys, this is just frustrating. Wife wont ride with me unless I get the AC working right, lol.

 

[RobbieD]

The vacuum reservoir should hold vacuum for a while, to operate the HVAC items, once the manifold vacuum falls off. You might have an issue there.

Sorry that I can't help with the vacuum line routing; a '98 is newer than what I beat on.

Wife wont ride with me unless I get the AC working right, lol.

Thanks! That gives me something to think about . . .

 

[Shran]

Can't help much with the vacuum lines, all my junk is quite a bit older than yours.

As far as your refrigerant pressures go - not sure if your gauge will show this but let's say it's low enough that the compressor won't kick on. You put some in and get your low side up to 40 and your compressor activates... what happens next is the compressor pulls refrigerant out and the pressure there will drop. It doesn't stay at 40 indefinitely - as the refrigerant moves through the system you will see some fluctuation in pressure, especially when there is not enough in there. How long did your compressor run and how much refrigerant do you think you've added at this point? You should see the compressor run for quite a while, not just a few seconds.

I would strongly suggest against buying the Harbor Freight gauge set - I have that one and it is a POS. I found several places where it was leaking during my last AC repair job. IMO you are better off buying quality ones (Yellow Jacket, JB, some others) or just pony up some cash to have a shop fix it... AC is one of those rabbit holes where you can either buy cheap tools and be frustrated with them or good ones and only use them once.

 

[Spidey300]

Can't help much with the vacuum lines, all my junk is quite a bit older than yours.

As far as your refrigerant pressures go - not sure if your gauge will show this but let's say it's low enough that the compressor won't kick on. You put some in and get your low side up to 40 and your compressor activates... what happens next is the compressor pulls refrigerant out and the pressure there will drop. It doesn't stay at 40 indefinitely - as the refrigerant moves through the system you will see some fluctuation in pressure, especially when there is not enough in there. How long did your compressor run and how much refrigerant do you think you've added at this point? You should see the compressor run for quite a while, not just a few seconds.

I would strongly suggest against buying the Harbor Freight gauge set - I have that one and it is a POS. I found several places where it was leaking during my last AC repair job. IMO you are better off buying quality ones (Yellow Jacket, JB, some others) or just pony up some cash to have a shop fix it... AC is one of those rabbit holes where you can either buy cheap tools and be frustrated with them or good ones and only use them once.

Thanks. When I added the recharge to get it to kick on the compressor ran steady for quite a while (10 mins?) before I shut it off. Probably an hour later I took it for a test drive and the compressor wouldn't kick on at that point. I haven't added the whole AC Pro can yet, so maybe I've added ~15-20 oz at most? Nothing got cold during the time the compressor was on but I was afraid to add too much.

I'm thinking I'm going to have to take it to a shop to leak test/diagnose/flush. Like you said, a quality gauge set is important and I'm not too experienced with AC work. I can replace parts/etc. but diagnosis and testing is probably best left to pros. I'm hoping the leak is in my condenser cause that (and the evaporator) are the two pieces outside the lines that I haven't replaced yet. Also hoping my compressor is still good.

I went ahead and ordered a blend door replacement kit and actuator, since it wasn't too expensive and it seems like I must have a faulty blend door if I'm getting heat in the cab with the temp turned to cold. I think my current actuator works but it's old/brittle and gummed up I'm sure and I have to take it out anyway.

 

[RonD]

You can cut a "window/door" in the air box behind the glove box, large enough to get your hand thru
There are videos for doing that, easily closed up with duct tape
Then you can move the blend door manually and/or watch if actuator/motor is moving it
The blend door's connection to actuator can break, so motor is working but blend door is not moving

 

[Spidey300]

Alright, took it to the shop and they told me my compressor is shot. Not sure about where the leak is coming from because they weren't able to charge it or run the compressor. Is it possible for me to still leak test it somehow? I'd hate to replace the compressor, accumulator, orifice tube, etc. and go to get it recharged just for them to find a leak somewhere else (I'm pretty sure the condenser is bad) and then I have to evacuate it, replace another part, and get new accumulator, orifice tube, etc. again. Should I just replace the condenser now too?

What brand of replacement parts do you guys recommend? I've been getting stuff off rockauto and it looks like they have four seasons, GDP, UAC, Denso... Is a new part best or should I try to find a good OEM one from the salvage yard? This will be my third compressor, I replaced it back in 2015 with a remanufactured one off ebay.

I'm still going to replace the blend door and actuator and try and track down the vacuum leak so the vent position controls/max ac will work. Thanks in advance

 

[RonD]

A shop will Vacuum test the AC system to see if it leaks, before recharging

You can replace any parts ahead of time, and then take it in to be tested, and then replace any other parts yourself if a leak is found
So you save money on labor and parts mark ups

Yes, anytime AC system is drained and exposed to outside air the accumulator/drier and orifice tube should be replaced
So replace the compressor(add oil to it) and new accumulator/drier and orifice tube
Then have it tested
If condenser is bad then replace it, you won't need to replace the new accumulator/drier and orifice tube again

AC doesn't work well with moisture inside the lines, because it steams and freezes with the temps involved
Thats the purpose of the Drier, it pulls out the moisture and hold it, when the system is exposed to outside air then more moisture comes in, an older drier may not have the ability to capture and hold too much more moisture

 

[Uncle Gump]

With the refrigerant in it now... you or they could leak test it.

 

[Shran]

How exactly did they determine that the compressor is shot without seeing it function...? I mean...it very well could be bad from your description about it making weird noises... but what exactly did they tell you?

I have used all of those brands of parts. Four Seasons seems to be decent quality. GPD is cheap junk IMO. UAC is somewhere in the middle. I used a Denso compressor recently, works fine, probably will be just fine, fit/finish was a bit lacking compared to the Motorcraft part it replaced. Of those I would probably not buy GPD ever again.

 

[Spidey300]

How exactly did they determine that the compressor is shot without seeing it function...? I mean...it very well could be bad from your description about it making weird noises... but what exactly did they tell you?

I have used all of those brands of parts. Four Seasons seems to be decent quality. GPD is cheap junk IMO. UAC is somewhere in the middle. I used a Denso compressor recently, works fine, probably will be just fine, fit/finish was a bit lacking compared to the Motorcraft part it replaced. Of those I would probably not buy GPD ever again.

They hooked it up to their machine and told me it wouldn't take any fluid so the compressor needed to be replaced. Is it worth taking my chances with a salvaged compressor? The other option would be a Motorcraft compressor w/ out clutch for about $75 more but I'd have to swap over my clutch components or buy new ones (another ~$80). Not sure how hard that is.

 

[Shran]

Gotcha. Makes sense.

No... I would not use a junkyard compressor unless there is a pretty good indication that it is a fairly new part and in a vehicle that was wrecked as opposed to just worn out. Just doesn't make sense to risk a used part that could grenade itself in a month or a year and then you'll be back at square 1.

Swapping the clutch parts isn't real hard. If I was faced with that situation though I'd probably buy the Denso compressor again. New one was only about $150 shipped. Denso is an OEM manufacturer for several car companies and so I figured that was probably the safest bet, I don't know if UAC/GPD/Four Seasons are or not.