My '85 MGM, "Maisa"

[Arquemann]

There's the green vacuum tree sticking up from the rear corner of the intake manifold, does it come off by pulling?
From said green beepboop a red striped vacuum line goes straight down to behind the manifold and into a metal pipe/line. I can't make heads or tails from the vacuum diagram on what this line would be or where it goes.

Couldn't vacuum test the stuff on said green tree, but pretty much everything else checks out. Even the vacuum leak from heater controls was minuscule, I doubt it has any effect. Biggest vacuum leak atm seems to be the throttle kicker...


Is "HCV" the hockey puck -looking reservoir on the inner fender, under the brake master?

I took off and capped the TAD/TAB vacuum supply line, capped the EGR solenoid outputs going to the EGR valve. Thinking about removing the Exhaust heat control solenoid crap too.

I wonder how much I could simplify the mess of vacuum T's, Y's and check valves... Just can't make any sense of the billion T's and check valves looping around and feeding eachother.
I'd need vacuum for the MAP, heater controls, throttle kicker solenoid and EVAP check valve? What needs a check valve?

If someone has pics of the CFI engine's backside, those would be greatly appreciated


@87GrandMarq plug wires are pretty new, so are the plugs and every other ignition component. I doubt wires are the issue anymore.

[gadget73]

I think the HCV is the flap in the exhaust pipe on the driver's side. It shuts when cold to force exhaust through the intake to warm it up faster.

[Arquemann]

Well, I didn't even realize I had the HCV, only time I've seen one before it was on a '84 (I think) truck 302, where the vacuum diaphragm housing was on the "outside" of the exhaust manifold. But there it is between the manifold and block in my car.
That also explains the red striped vacuum line that I asked about earlier.

So the HCV gets vacuum from the green thingymabobber thats on the corner of the intake manifold? How is it supposed to be controlled? Circled in image:

Or is the circled thing even a vacuum source at all? Are there I can't find any info or good images of the CFI intake manifold.

Is the "VCV" in the image the firewall mounted beige vacuum distribution block (up and center) or something completely else? I can't really figure out how the HCV gets controlled if it just gets vacuum all the time.

Also I did some strategic deletion to better represent the current situation of the vacuum mess. (the intake snorkel flap is busted and has been disconnected before I even got the car, I have zero clue on it's correct plumbing)


DOES MY ENGINE HAVE VACUUM SOURCES OTHER THAN THE METAL TRUNK BEHIND THE EGR VALVE, PCV PORT AND PURGE CV THING?

Lastly, can I just unplug the HCV? or does it close without vacuum?

[gadget73]

The tkick solv should be the solenoid valve that sends vacuum to the throttle kicker.

VCV I think is a temperature-controlled vacuum valve. Looks like it switches from exhaust flapper operation to evaporative canister purge depending on engine temperature. Basically it has a plunger inside so when cold vacuum goes one way, when hot it goes the other way. No idea what temperature it switches at but if it leaks or doesn't switch correctly it will do stupid things.

reasonably sure the HCV is spring open, vacuum closed but confirm that. If you have to, wire the flap open and plug the vacuum line.

[Arquemann]

UGH,
Since me digging around checking the vacuum lines and stuff, I hadn't any time to drive until today.

Now my AC compressor runs constantly unless the heater is set to OFF, Vent or Floor.
And I only get hot air...

Did I yank some vacuum line loose under the hood, or is something finally conked out in the AC system?

[sly]

Check the vacuum tree. There should be a check valve with two lines coming out of the end away from the tree. One goes to the soup can on the driver fender (vacuum reservoir) and the other goes to the HVAC system. Even if that check valve is bad, the system should work fine at idle (high vacuum). If any of that is not connected, or a line is broken, you'll get heat through the defrost vents only as that's the default setting with no vacuum to the HVAC system. Under the hood, the blend door is actuated by vacuum if you have the automatic temperature control. Also, there's a hose from the cabin temp sensor to the firewall on the passenger side behind the glove box. If that comes off the firewall, you'll get weird happenings.

[Arquemann]

So uhhhhhhh. I fiddlefucked with the stuff. I did nothing, or I'm pretty sure I changed nothing. I don't know maaan... But but but now the heat/cold works again.

The line that sly mentioned going from the check valve to the HVAC system still leaks vacuum, nothing new there. also the check valve is good.


BUUUUT still the AC compressor stays on constantly, like going non-stop for as long as you let it, which isn't okay. 45 seconds of idling and shutting it off has drier/accumulator hissing like a wild cat and getting reaaaaal cold. I had to unplug the low pressure sensor to stop it doing that.
So what in the nine hells is causing that now?

I do have ATC btw.
What does the cabin temp sensor look like, couldn't figure out where it is / see it by sly's description. An image would be bloody great too.

[87gtVIC]

So uhhhhhhh. I fiddlefucked with the stuff. I did nothing, or I'm pretty sure I changed nothing. I don't know maaan... But but but now the heat/cold works again.

The line that sly mentioned going from the check valve to the HVAC system still leaks vacuum, nothing new there. also the check valve is good.


BUUUUT still the AC compressor stays on constantly, like going non-stop for as long as you let it, which isn't okay. 45 seconds of idling and shutting it off has drier/accumulator hissing like a wild cat and getting reaaaaal cold. I had to unplug the low pressure sensor to stop it doing that.
So what in the nine hells is causing that now?

I do have ATC btw.
What does the cabin temp sensor look like, couldn't figure out where it is / see it by sly's description. An image would be bloody great too.

It is located passengers side just above the glove box. You can see a cut out in the dash trim where it samples interior air temp. To gain access to it you kinda need to remove dash pad and fiddle with it from either up there or from under the passengers side foot well. Its not the easiest to access. Two 7/32 or 9/32 fasteners iirc.

[Arquemann]

Am I going on a goose chase finding the cabin temp sensor? Since my temperature control seems to be working correctly again...

Does the ac compressor have a thermostatic switch? Or what else controls the compressor activation?
Anything to check? I have literally no clue on how to move forwards on this, except for the cabin temp sensor maybe.

I have never used the auto fan setting on the heater, but the automatic temp control is kinda nice when it works.

[Tiggie]

Need more specifics about "constant". How long did it run? Did you change the rpm at all?

At idle and certain temperatures, you might hit the sweet spot of very long times on between cycles, if it cycles at all. Bring up the RPM and it should cycle. Getting frosty is a good sign.

[sly]

The AC compressor does not have any switches. There's the low pressure switch near the dryer and that's it. Once the refrigerant reaches a steady state (typically a few cycles after initially turning on), the compressor regularly runs constantly. This is on 134a systems. On R12 systems, this can also be the case on hot days. Cycling will only occur if pressure actually gets below about 15psi on the low side. If you put a gauge on the low side and it does get below 10psi, the low pressure switch is bad. Replace it and you should be fine. If the line never gets below 40psi, the orifice tube may be blown out.

Without putting a gauge on the system, you're not going to know what is keeping the compressor on.

[Arquemann]

Hmmm, this needs further testing then.

Usually the compressor kicks on for maybe 10-15 seconds, shuts off for maybe double that and kicks back on again, and that goes as long as I have the car running.
Today it just runs constantly, as in the clutch is engaged non-stop and the compressor makes a helluva lot of noise. Longest I had it run for about a minute straight, that was all idle though.

[sly]

Definitely need gauges. These systems are designed to run constantly. Obviously will cycle more in cooler weather, but will probably still find a stable state for minutes at a time.

[gadget73]

thats nothing vacuum related. The switch to turn on power to the compressor is in the climate control in the dash. Guessing its messed up, though I've never run into one that failed in that specific way. It should only be fed power when its in AC or defrost modes. Temperature control is independant of compressor power. You can turn the thing to full hot in AC mode, you'll get hot air and AC compressor.

unless someone has been in the dash and fucked around with the wiring, which is totally possible.

If it cycles, thats the low pressure switch cutting power to the compressor. If the switch failed shorted or the wires to the switch melted together it might do this, but you still should not be getting any power to the compressor unless you have AC mode selected. Pressure switch screws into the black or silver can on the passenger sie of the engine compartment, right against the firewall. Should be poking out of the side with a 2 wire plug on it. I've had multiple junk pressure switches, just replaced one on the Continental last week that was keeping the AC from running. They can stick on though.

[Arquemann]

Well good news!

It fixed itself! The ac compressor and heater behaviour has gone back to normal. And normal being what it has been for the last two years. At this point I don't really know if I should care if my normal is wrong or right, since it works
Now it does the basic cycling thing couple times a minute and I get warm, cold and inbetween and all the heater controls seem do what they're supposed to.



So, back to the smog delete. What length belt should I get for the pump delete? Or do I need to route the belt different or need an idler in place of the smog pump?
I'm probably going to leave the metal air tubes in place for now and cap them with something. I'd really like to remove the air hoses and solenoid mess and the pump is coming out since the pulley wobbles alot.