FJ60 Air conditioning troubles.

[hank14]

I am trying to trouble shoot my A/C system before the heat and humidity hits here in TX. This is a bit long, but in searching past threads, I didn't see much in depth diagnostic info on the A/C system. I have the FSMs, but didn't know how much of the diagrams were still appropriate since my system has been converted to R134. Here's the background:

I bought the 60 last August. A/C blows cold then and now.
Past records show that the entire A/C system has been worked on twice, inclucing R134a conversion and new compressor by a shop in 2003 (about 22,000 miles ago).

Problems:

1. When traveling down the highway with the A/C on, the system will "freeze up" where there is frost on the plastic duct below the dash, and the fan will quit blowing. If I turn off the blue a/c switch, the fan will eventually start blowing and the system will unfreeze. This hasn't been too much of a problem, since I am rarely on the highway. The relay under the dash has never tripped or needed to be reset.

2. In town, when I turn on the A/C, the compressor turns on, the VSC switches and the A/C idle up on the carburetor increases the RPM at idle to about 900 (which I have set using the FSM directions). While idling or after driving for a few minutes, however, the A/C idle up VSV kicks off, and the idle goes back to 600 (or a little less since the compressor is still engaged). If I hook direct vacuum up to the idle up diaphragm in the carb, the RPMs go up to 900 again. I have removed the idle up VSV and tested it per FSM directions, and it seems to work fine.

3. The compressor comes on every time I turn on the A/C, but it does not cycle on and off- the clutch stays engaged the whole time the A/C is switched on. I have tried adjusting the blue A/C amplifier, but it does not seem to make a difference. I diagnosed low coolant based on bubbles in the site glass. I bought a gauge and some R134, and it was indeed low. I added some 134, but didn't quite know what I was doing, so I didn't get it filled all the way up. This did not seem to change the compressor cycling- it stays engaged the entire time the A/C is switched on.

I think all these problems are related, but am confused by the FSM diagrams and troubleshooting. How can you test the A/C amplifier? Could this be the problem?

 

[UpsideDown]

It sounds like you have a faulty pressure switch... though there may be other problems as well.

The switch is a bit of a bugger to replace since (in my 1987 HJ61 at least) you have to take apart a fair bit of the system to get at it. Also, there is no valve behind the pressure switch to prevent the loss of your refrigerant while the switch is missing... best to drain the system of refrigerant (use a recovery unit), then replace the switch and re-evacuate the system and do a proper refill.

Be quite careful not to overfill your system. The sight glass is not a surefire way to get things right - you really must either weigh the refrigerant or use gauges (or get an expensive machine to do both).

hth.
John

 

[bigboss]

just maybe

you say the system has been worked on twice is there a chance that some one has put a direct feed to the compressor from the switch bcause you mentioned that the charge was very low and in theory that should automaticaaly imobilize the comressor unless the ubove has been done and there for the thermostat in null and can not cycle the comressor acording to the temp at the evaporator just a thought mate good luck

 

[hank14]

Both good thoughts- thank you.

The initial pressure was about 15 psi (low range of 0-22). I think the problem when trying to add refrigerant was I didn't have the can right side up- it was upside down. I did get some coolant in there, as the sight glass now only has a few bubbles in it, but the pressure is around 19-20.

In the FSM, it does not have a diagram of the 60 series single A/C component locations- only the 70 series and 60 series dual a/c on pages AC-22 and A/C 23. It does show the pressure switch being located below the glove box, above the a/c amplifier on page AC-35. I will try testing it tonight.

There does not seem to be a test procedure for the a/c amplifier. I suppose it needs to be replaced to see if the old one was faulty?

 

[cruiser_guy]

Yep, I agree with the first poster. It sounds like the pressure switch. The compressor should cycle on the switch or if there is a thermostat on the evaproator that should help keep it from freezing up and it would cycle the compressor.

My A/C is on R134a and it works just fine, even all day on the highway.

The charge with R134a CANNOT be verified by bubbles in the sight glass the same way that R12 could. If you have no bubbles you have too much charge which is not good either!

 

[hank14]

you say the system has been worked on twice is there a chance that some one has put a direct feed to the compressor from the switch bcause you mentioned that the charge was very low and in theory that should automaticaaly imobilize the comressor unless the ubove has been done and there for the thermostat in null and can not cycle the comressor acording to the temp at the evaporator just a thought mate good luck

BigBoss may be a newbie to mud, but he is the WINNER!!!
I removed the glove box looking for the pressure switch and found a wire run from the yellow wire form the A/C switch to the compressor. I also found where the compressor wire had been disconected. I reconnected it, and the compressor cycles like it is supposed to.

Here's the jumped yellow wire from the A/C switch. The other end goes to the pressure switch with the yellow green wire from the A/C amplifier.

Here's where the jumped wire was connected to the compressor wire connector.

Here's the top of my compressor. Ain't she purdy!

 

[hank14]

The charge with R134a CANNOT be verified by bubbles in the sight glass the same way that R12 could. If you have no bubbles you have too much charge which is not good either!

Thanks for the tip, cruiser guy. After searching about 134 coversions, I didn't see anything mentioning this. I did notice the pressures listed in the FSM were higher for R12 than they are for R134a. I may break down and take it to an A/C shop for evacuation, leak test, and recharge. This stuff is too expensive to screw up.

 

[hank14]

Now the obvious question:

Why would a shop bypass the pressure switch when installing a new compressor, to the tune of a receipt totaling $1200+? What is the benefit, and is there harm reconnecting it to stock?

 

[cruiser_guy]

There is no good reason why a shop would bypass the pressure switch when they deliver the vehicle and many bad reasons! They might bypass it during their work so they don't need to wait for the compressor to cycle.

 

[hank14]

There is no good reason why a shop would bypass the pressure switch when they deliver the vehicle and many bad reasons! They might bypass it during their work so they don't need to wait for the compressor to cycle.

Do you think they may have been trying to hide another problem or a quick fix for something else? I actually have the receipt for the shop from the PO- I think I'll call them and ask.

 

[cruiser_guy]

Do you think they may have been trying to hide another problem or a quick fix for something else?

I doubt that. Any A/C shop knows that if the compressor runs continuously it will ice up especially in low load conditions which is exactly what happened to you.

 

[CruisinFJ60]

im glad you found why it wasnt cycling that was my first thought as well and that it had been bypassed for some reason.

also something to note any time the compressor freezes (more so the lines going back to it (so in this case from the expansion valve to evaporator to the compressor)) you run the risk of major damage to the compressor and even more so in your case where the evaporator has so much ice on it the fan stops. reason is once they ice over solid like that it restricts the flow back to the compressor but yet the compressor would still be running well if flow is restricted on the low side (frozen side) then that also mean nothing is going into the compressor like OIL (or 710 for u blonds out there) no oil means damage can occure at a very high rate. but it sounds as if you found it before anything happened.

as far as your idle up not always working... well sounds as if it may be bad but testing good (it can happen) or you have a small vac leak someplace (most likely the problem) but overall it wont damage anything when at a lower rpm the compressor is moving less freon so it may not be quite as cold in trafic and if it drops to low liek to the point of killing the engine (usually only if you are already having other problems that deal with how the vehicle runs) then obviously that can be embarassing and annoying. but other than that it wont do any harm.

so check your vac lines then check em again. otherwise sounds like you did your reasearch and are getting it slowly but surely figured out and maybe even learning something new along the way.

Trent

 

[bigboss]

if you ask me the newbie id say that they didnt actually knoww the workings of the air con system in the first place but there is many tools on the net to tell you how to retrofitt a r12 system to a r134a system does cost a lot of money if you do do it i doen it and the biggist bproblem was refilling the amount of gas to put in it ended up tacking 800 grams to fill if this helps you good luck let us know what the shop say it will be interesting cheers big boss by the way thanks for the photos this really makes it worth helping your mates out some times you just need to get an outside perspective hey any time mate

 

[bigboss]

hey hank14 thingking about it now mate i think what you were experiancing whith the engine idle hassle was actually correct ,the electronic contol was getting the call from the thermostat to activate the engine up sequence and engine down as if the compressor was suppose to be doing the same in other words the eng was cycling to the thermostat but not the comp because it had feed all the time engaging it ,wat you think about this idea let us know i would like to get this sorted for you if we can can you include a picture of the ac amplifier to please if possiable thanks

 

[hank14]

Here's three pictures if anyone's interested:

1st- measuring refrigerant pressure (amount of r134a)

Here's the a/c amplifier as viewed from under the left side of the glove box

Here's the top of it from inside the glove box opening with the glove box removed

From page AC-35 of the 1984 LC Chassis & BOdy FSM:


Air conditioner Amplifier

CHECK ENGINE SPEED DETECTING CIRCUIT

a) Run the engine and operate the air conditioner.
b) Check that the magnetic clutch disengages at the specified engine revolution.

Cut off RPM: 600-700 rpm

If the cut-off rpm is too high, turn the adjusting knob clockwise to adjust.
If the cut-off rpm is too low, turn the adjusting knob counterclockwise to adjust.

 

[hank14]

Thanks everyone for their input. I called the shop that did the install in 2003, but they are now a bar and grill- Austin really is going to hell in a handbasket!

Anyways, since correcting the bypassed pressure switch, the A/C idle up solenoid is working porperly and the compressor clutch is engaging and engaging regularly- maybe too frequently? I timed it, and it engages for about 15 seconds and disengages for about 9 seconds consistenly at an idle of about 1500 rpms.

Is this about right?

Also, when adding r134 refrigerant, about how long should it take? do you leave the valve open the whole time, or close it when the clutch engages or disengages?

What I found was when the clutch was engaged, the pressure would decrease to about 20-25 psi, and when the clutch disengaged, the pressure would increase to about 35-40, and slowly rise towards the upper end of the normal level, only to drop back when the clutch engaged again.

Once I finished (I tried this for about 5-7 minutes) and the bottle still had not emptied completely- maybe 1/2, the pressure was about 20-22 psi.

Any other tips?

 

[CruisinFJ60]

leave valve open the entire time when filling.

when compressor is running and clutch engauged. you want a low pressure reading of around 25-35 psi depending on outside temperature (25-30 is good for temperature round this time of year in texas tho i personally would shoot for 30psi) and a high side pressure of around 200psi.

in the middle of summer with 100*F+ days that we see in texas expect a low pressure reading around 30-35 psi and a high side pressure of around 225-250 psi while compressor clutch is engauged.

 

[bigboss]

hank 14 could you please explane to me why you are using a single gauge to test the system i have alwayas used an two way manifold to check the pressure at the high and low sides of the system this gauge you have conected is it on the blue side or red side hoses another thing is we need to under stand that it is temp we are refering to not always pressure but ther is direct coefficients i have a list some where i think but will only aplly to the two way manifold gauges

 

[hank14]

hank 14 could you please explane to me why you are using a single gauge to test the system i have alwayas used an two way manifold to check the pressure at the high and low sides of the system this gauge you have conected is it on the blue side or red side hoses another thing is we need to under stand that it is temp we are refering to not always pressure but ther is direct coefficients i have a list some where i think but will only aplly to the two way manifold gauges

The main reason I'm using the single gauge is because I'm cheap. Otherwise, I'd be on the 200 series Landcruiser Forum.

No, really it's because I thought that was all that was required. I bought an r134 service kit from NAPA Auto Parts to check the low side pressure and refill the system.

I have the pressure vs. temperature charts in my factory service manual.

I still think I'll be better off taking it to someone who has the proper gauges and ability to leak test and recharge the system. $$$$$$

 

[bigboss]

ha ha wouldnt we all hey all good you do what you can with what you have well look at it this way as long as you covered all the basses the cost can only be less and the added experiance of know all the lingo when you get it back with the account cheers mate all the best