Noob to AC work needs help

[VincentGsrq]

New member here with a 3rd gen 1998 2.7 2wd SR5, I bought it with the AC not working, the clutch does not engage at all, my 1st stab at AC service was to replace the drier, as I am in Florida it seemed prudent, I vac'd the system down for about an hour with a 4cfm pump, then left it for an hour and the manifold stayed at 28 bar, I then tried to recharge the system, opening only the low side and it will not accept much refrigerant at all, maybe 3-4 oz tops, the compressor does not kick on, the motor is running, the AC switch on and lit.

I am wondering if I can do a bypass to the exciter coil to get the compressor to engage. Or to now replace the expansion valve just cuz, vac it out and start over.

Any help will be greatly appreciated.

Thanks in advance,

Vince

 

[RandyBobandy]

I haven’t fixed my AC yet because it’s still winter here, but this is what I learned fixing it on a mustang I used to have

The compressor needs to be on for it to take any refrigerant, and there’s usually a sensor that keeps the compressor from turning on if there’s no or low refrigerant in the system, at least there was on the rustang, so what I ended up having to do was use a paper clip to jump a connector and make the compressor cycle so I could add refrigerant, and once I got it full it worked fine since the low pressure sensor was no longer keeping the compressor from cycling

That’s my experience with working on a huge piece of crap ford, but it might give you some insight on your issue

 

[19963.4lsr5]

How cold is it where you are in Florida? Your low side switch could be bad.....

I only charge a system when it’s above 80 outside.

When you are trying to charge the system what pressures are you seeing on your high and low side gauges? You are opening the low side valve to charge the system, correct?

make sure you are operating the gauge set hand valves correctly. Hand valve closed isolates the gauge from the can. So if you evac’d the system with the low side valve turned in all the way all you did was pull a vacuum on the gauge set.




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[jgue467]

...
Or to now replace the expansion valve just cuz, vac it out and start over.
...

Always replace the expansion valve when recharging system.

 

[VincentGsrq]

Outside temps were low 80s and I vac'd with both sides open, then closed both sides for the vac test, when I went to recharge, motor on, ac switch on and 28 bar of vac on the system, I pressurized the line with refrigerant before opening only the low side on the manifold, the low side gauge went up to approx 8 o-clock position and the high side did nothing, I will replace the expansion valve today and restart the whole process after this cold front passes (an hour of vac and an hour of test), today's high is only low 70s, there is no obvious spot to jump the exciter on the compressor harness, I will look and see if the low limit switch can be bypassed
Thanks for the help, I will report back

 

[MaineRunna]

Outside temps were low 80s and I vac'd with both sides open, then closed both sides for the vac test, when I went to recharge, motor on, ac switch on and 28 bar of vac on the system, I pressurized the line with refrigerant before opening only the low side on the manifold, the low side gauge went up to approx 8 o-clock position and the high side did nothing, I will replace the expansion valve today and restart the whole process after this cold front passes (an hour of vac and an hour of test), today's high is only low 70s, there is no obvious spot to jump the exciter on the compressor harness, I will look and see if the low limit switch can be bypassed
Thanks for the help, I will report back

Probably just low system pressure causing the low pressure cut off switch to disable the compressor. The magnetic clutch, fuse or the relay could also be bad. Try jumping the cut off switch or the relay to force the compressor on. It should take refrigerant then. Also will tell you that the circuit it good.

 

[19963.4lsr5]

I’ve never had to jump a low switch to charge a system. Including my 4Runner after I put the engine in.

What pressure is 8 o clock.

The vacuum should have pulled enough refrigerant into the system to close the low side pressure switch and energize the clutch. The pressure will rise and fall as the compressor cycles on and off. Running a little longer each time until there is enough in the system to keep the suction pressure above 25psi or so.

Was the system empty before you started vacuuming it?

You said the high side stayed at zero? Even if the expansion valve was blocked with debris from a grenade’d compressor the pressure still should have equalized between the high and low side through the condenser.


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[Soren96]

Agreed, I’ve also never needed to jump the compressor To get it to allow a charge. Most of the capacity is in the rest of the system. Could be too much oil in there, for example, if you only vac’d and then added the type of refrigerant that contains oil (big no-no on a full system), or if previous owner did that. Assuming it’s not debris or a fragged compressor, you can try turning the compressor side by hand to push some oil around and give the refrigerant a chance to equalize, but that shouldn’t be necessary. The next step (before replacing anything else) would be to vac it down again, then pull the lines and drain/purge all oil from the system With one of those compressed air loaner things and a no residue cleaning fluid. Inspect that oil for any bits. Then turn the compressor by hand and feel for anything “not right”. You’ll also want to empty it of any oil as well. If all is good, you can then add the correct amount of oil, maybe get a new dryer for good measure(sorry), vac and charge again.

 

[DaveL]

I have worked on numerous cars with A/C. It is not that uncommon for systems that have been pulled all of the way down and completely evacuated to need some help by jumpering the compressor to initially pull some refrigerant in to overcome the low pressure cutout switch (that protects the compressor on low charge). There is also some variance in the setpoints of the low pressure switches installed. Most service manual / shop manuals will have a few steps to show you how to jump across the clutch relay coil to energize the coil. When I am investigating the initial stages of a non-working system it is helpful to know how to do this anyway..... with the engine off you can jumper the contacts across the A/C relay and listen to hear the clutch engage.... if you can't hear it (a large click) you probably have a bad clutch coil. Because it is relayed it is usually wired directly to the hot side of the fuse box and you don't need the ignition on to energize it with a bypass around the contacts. I say probably because now days a lot of clutch circuits will also have a protective thyristor (usually mounted on the compressor itself) that senses whether the compressor is too hot and will also open the clutch circuit to keep the compressor from destroying itself. Haven't seen many failures of this.

 

[VincentGsrq]

1st thing I will try is to hand rotate the compressor, thanks.

The 8-Oclock position on the needle was approximate and since the compressor never came on there was no cycling at all, the high side never moved.

I have not added any oil at all nor used refrigerant that contained oil, I always thought you only add oil when you change the compressor, if you dont install one that is pre-oiled.

With the car off I will check at the relay if I can excite the magnetic clutch, if the compressor does rotate freely by hand.

Thanks again to all suggestions

 

[19963.4lsr5]

1st thing I will try is to hand rotate the compressor, thanks.



The 8-Oclock position on the needle was approximate and since the compressor never came on there was no cycling at all, the high side never moved.



I have not added any oil at all nor used refrigerant that contained oil, I always thought you only add oil when you change the compressor, if you dont install one that is pre-oiled.



With the car off I will check at the relay if I can excite the magnetic clutch, if the compressor does rotate freely by hand.



Thanks again to all suggestions

In my opinion the high side should have moved. If you measure the static system pressure what do both gauges read? They should be the same when the compressor is not running and system is cold.


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[DaveL]

Most replacement compressors have an oil recharge in them so that you don't have to check or add oil to them but it just depends on the supplier.

Oil is normally distributed witihin the system (carried along by the refrigerant) so the total amount of oil is more than just in the compressor.. If you replace individual components of the systems such as drier, evaporator, condenser, etc. the service manual will normally specify a small amount of oil be added based o the size of the component (e.g. 50 - 100 CC of oil). It will be slightly different for each component. If you don't replace it then that oil will be replaced by the total amount of oil in the system and could show up as a low level in the compressor. Different manufacturers also specify different viscosity oils for their their cars...... although most auto suppliers will carry a generic replacement that is "close enough" if you don't use too much of it to blend in within the existing system. But if you add oil you might want to research it to see what they specify and get something close to it. Almost none of the dealer service departments use manufacturer refrigerant oils so that probably tells you that its ok to use aftermarket oils. The only car that I know makes a really big deal about this is VW..... and their refrigerant oil is very expensive ($90 / pint)..... or used to be.

 

[VincentGsrq]

I changed out the expansion valve, found an ancient rodent nest in the bottom of the evaporator housing, cleaned it all up reassembled, vac'd system for 40 mins, leak tested for an hour, started it up and it took almost 9oz of 134a, low side got up to 75psi high side was around 20psi, compressor never kicked on, I unplugged the hot lead on the compressor and hooked a jumper to + and it did not start the compressor:-(

Rather than change out the magnetic starter at $65, I am thinking of changing the entire compressor for $135-150.

I bought an AC compressor relay but cannot find an "ac relay" in the relay box, there is one marked "heat" and it is a different relay type, the one they sold me looks like all of the others ie EFI, Tail, Head, power outlet.

Rockauto has an AC kit that has evaporator, condenser, compressor, drier and expansion valve plus gasket set for $250.

I have been told that either the condenser or the evaporator can have accumulated blockage.

I did find that the high side was full of leak test dye, the PO was likely the cause of that, but I don't know how he got it into the high side, I would think the cans with the single gauge only connect to the low side, but I don't know.

I would welcome any advice. While this should be the season where I have plenty of time, it is hot here in Florida, lol.

TIA
Vince

 

[Bad Luck]

You need a compressor

 

[VincentGsrq]

I bought the OEM Denso at Rockauto

 

[VincentGsrq]

In the end I replaced everything, evaporator, expansion valve, low pressure switch, compressor, drier and condensor. I also replaced all 3 drive belts, both coils and plugs and wires. With the exception of plug wires and iridium plugs everything was OEM.

The Toyota shop manuals do not list the exact amount of oil for the compressor, only the amounts for two other components, so I added that amount to the oil in the compressor as well as a small amount of dye.

All 4 of the the cap head bolts on the condenser and drier broke upon removal and were replaced. The compressor came with new bolts holding a blank plate onto it and those two hose connections are the only ones I did not re do because I knew the bolts would break and I did not order that specific part, nor did it come with the compressor. All of the gaskets and seals were replaced but those two o-rings.

I vacuumed down the system for about 90 mins, then did a vac test for 60 mins, no loss of vacuum at all.

I was surprised how long it actually takes to get the new refrigerant into the system. Ambient temps were in the mid 80s. The plate reads between .6kg and .7kg of 134a, I ended up with 648g. The main register was blowing 50 degrees and sweating like a pig by the time I was done.

I had been without AC for over a year with my previous vehicle as it was not cost effective to repair. Driving home yesterday was probably the 1st time driving with AC in about 2 years (not counting the Celica and the wife's car), and I was determined not to do another summer here in FL without it

I love my T4R and I initially chose it because I am a lifelong Toyota fan, mostly Tacos/Hilux, I also have a Gen2 Celica with a 22r and I plan to do most if not all of the wrenching from here on out.

My next project is the clear coat on my hood, I really have grown fond of the Desert Dune Metallic Pearl color and I think I can get the old clear coat gone enough and save the original paint and just re-coat with some clear coat I have leftover from a previous project.

Thanks for all of the advice and for this site.
Vince

 

[BamaDrewski]

New member here with a 3rd gen 1998 2.7 2wd SR5, I bought it with the AC not working, the clutch does not engage at all, my 1st stab at AC service was to replace the drier, as I am in Florida it seemed prudent, I vac'd the system down for about an hour with a 4cfm pump, then left it for an hour and the manifold stayed at 28 bar, I then tried to recharge the system, opening only the low side and it will not accept much refrigerant at all, maybe 3-4 oz tops, the compressor does not kick on, the motor is running, the AC switch on and lit.

I am wondering if I can do a bypass to the exciter coil to get the compressor to engage. Or to now replace the expansion valve just cuz, vac it out and start over.

Any help will be greatly appreciated.

Thanks in advance,

Vince

The first thing to check when the compressor is not engaging is the pressure switch under the hood on the passenger side. These do go bad and they are a simple replacement. (Trust me - I just went through it)

 

[T4R_2000]

In the end I replaced everything, evaporator, expansion valve, low pressure switch, compressor, drier and condensor. I also replaced all 3 drive belts, both coils and plugs and wires. With the exception of plug wires and iridium plugs everything was OEM.

The Toyota shop manuals do not list the exact amount of oil for the compressor, only the amounts for two other components, so I added that amount to the oil in the compressor as well as a small amount of dye.

All 4 of the the cap head bolts on the condenser and drier broke upon removal and were replaced. The compressor came with new bolts holding a blank plate onto it and those two hose connections are the only ones I did not re do because I knew the bolts would break and I did not order that specific part, nor did it come with the compressor. All of the gaskets and seals were replaced but those two o-rings.

I vacuumed down the system for about 90 mins, then did a vac test for 60 mins, no loss of vacuum at all.

I was surprised how long it actually takes to get the new refrigerant into the system. Ambient temps were in the mid 80s. The plate reads between .6kg and .7kg of 134a, I ended up with 648g. The main register was blowing 50 degrees and sweating like a pig by the time I was done.

I had been without AC for over a year with my previous vehicle as it was not cost effective to repair. Driving home yesterday was probably the 1st time driving with AC in about 2 years (not counting the Celica and the wife's car), and I was determined not to do another summer here in FL without it

I love my T4R and I initially chose it because I am a lifelong Toyota fan, mostly Tacos/Hilux, I also have a Gen2 Celica with a 22r and I plan to do most if not all of the wrenching from here on out.

My next project is the clear coat on my hood, I really have grown fond of the Desert Dune Metallic Pearl color and I think I can get the old clear coat gone enough and save the original paint and just re-coat with some clear coat I have leftover from a previous project.

Thanks for all of the advice and for this site.
Vince

I was laughing as I read this post. I had most of the same problems with my system, including the little nest down in the box. How much oil did you end up putting in, did you drain and measure what was in the new compressor, then refill it with PAG 46? What is your temp at the vents? Mine is at Appox 50 degrees, but I have seen where some say they got theirs down to the mid 30's (50 degrees in the face is nice, I think 30's would be a little too cold). Also, how did you determine the R134 fill.