AC system low and high side pressures.....

[opie74]

AC system low and high side pressures and oil capacity question

With my impending AC work coming up, I bought a manifold set from HF. Took some static and running readings tonight and I think I have the running readings right, not sure about the statics....

Static readings were 110psi on the low side and 160psi on the high side. Temp was about 85.

Running readings were 35-42 on the low side and 400-450 on the high side with the pressure bouncing around on the high side and both sides increasing if I bring the idle up.

Im pretty sure based on what Ive read the high high side pressure is from blockage somewhere in the system. Could the sounds my compressor is making be from the relief valve in the compressor?

But the static readings have me stumped... They should be equal.

Also... What pag oil do I need for the compressor if I do in fact replace it?

 

[CanadianTRD]

Remember, ALWAYS take A/C readings with the RPM's about 2000.

Normal for low is about 35psi

Normal for high is about 200psi + the ambient temperature in F. So for you about 285.

Sounds to me like you have clogs in your condensing coil, and/or bad coil fin..check for bent or blocked fin. Also double check your fan is running, if your fan fails your pressures will skyrocket.



If it is not your condensor coil, it could be your expansion valve. http://www.rockauto.com/catalog/moreinfo.php?pk=2994291

If not your expansion valve, it could be your heater is stuck open and running hot coolant through your evap coil at the same time.

 

[opie74]

With the idle increased, low side was between 42 and 45 and the high side between 450 and over.

Blend door is functional. I do get some cold air, but it eventually warms.

I also think Im overcharged a bit. But what Im really curious about is the sound coming from the compressor. Do these have relief valves in them? Clearly my compressor is working, just making sounds it shouldnt be making.

 

[CanadianTRD]

A LITTLE overcharged, (negligible) but your splits are consistent.

Here is what I do know, I'll leave the rest to the other guys...

A fully functional compressor can still make grinding noises from the shaft/bearing/pulley. Any of these components can get dirty/bent and start grinding.

Here are all the parts you COULD replace, which ones is your call:

Vehicle: 1997 Toyota 4Runner



A/C Condenser
Denso W0133-1742029 $83.85 $83.85

Warehouse: B (Ships: Ground Only) (Please Note: cannot be shipped to Alaska or Hawaii)
Qty Description Brand Sku Price Total

Vehicle: 1997 Toyota 4Runner



A/C Expansion Valve
A/C Expansion Valve
Denso 7920-05169612 $29.85 $29.85

Vehicle: 1997 Toyota 4Runner



A/C Receiver Drier
New Receiver Drier -- DENSO is the OE supplier for this vehicle; OE-specified O-rings included.
Denso 7920-05169618 $15.35 $15.35

Vehicle: 1997 Toyota 4Runner



A/C Compressor
New -- DENSO is the OE supplier for this vehicle; OE-specified O-rings and Oil included.
Denso 7920-05052036 $224.85 $224.85




If you have a coupon code, enter it here:

(optional)
Subtotal: $353.90
Shipping Total: FREE
Total:

In my opinion it sounds like valve/condensor coil/fan to me.

 

[Singtoe]

Sounds like the expansion valve is stuck shut.

Did you add Freon to system? If you didn't then it can't be overcharged.

 

[opie74]

A LITTLE overcharged, (negligible) but your splits are consistent.

Here is what I do know, I'll leave the rest to the other guys...

A fully functional compressor can still make grinding noises from the shaft/bearing/pulley. Any of these components can get dirty/bent and start grinding.

Here are all the parts you COULD replace, which ones is your call:



In my opinion it sounds like valve/condensor coil/fan to me.

I have a new compressor, valve and drier that arrived today. Condensor should be here tomorrow.

The noise the compressor is making I have never heard any other compressor make. Sounds like a sloppy chain in a transfer case.

Sounds like the expansion valve is stuck shut.

Did you add Freon to system? If you didn't then it can't be overcharged.

I did add 134a to it because it was a bit low. It took almost the entire can and it was a large one. I do have a leak where the fittings bolt on the drier. Small leak but a leak non the less.

 

[CanadianTRD]

I have a new compressor, valve and drier that arrived today. Condensor should be here tomorrow.

Well what do you need us for then!? lol :shrug:

 

[opie74]

Well what do you need us for then!? lol :shrug:

Yeah yeah, I know. Originally I thought the compressor was going out due to the noise and the gradual lack of cold air. So I ordered parts prior to properly diagnosing the problem.

Mainly curious on the noise and the discrepancy in the static readings. I haven't been able to find anything on the net as to why the static readings have a 50psi difference. Im going to replace everything regardless, but I like to know what means what when I find something that needs explaining.

Its a curse, ask my wife.

 

[Singtoe]

Nothing like throwing money away.

If your compressor is blown, it blew chunks of debris in to your expansion valve making it malfunction.

Fix the leak, replace the compressor, drier, expansion valve and flush your condensor and evaporator and you should be good to go.

 

[opie74]

Nothing like throwing money away.

Aint that the truth. If I did not have a camping trip planned in the middle of August, I would not be doing this right now. Its all for a good cause though. Wife says I gotta keep this till it falls apart.

If your compressor is blown, it blew chunks of debris in to your expansion valve making it malfunction.

Fix the leak, replace the compressor, drier, expansion valve and flush your condensor and evaporator and you should be good to go.

Nice thing is Im going to replace the condensor too, so I dont need to worry about trying to flush it. I may go ahead and pick up an evaporator too, since I have to pull that out to get the valve out. All the lines look good, no leaks there.

I need to win the lottery.

 

[curtperry]

opie74 you have a little bit of OCD huh? :wink2:

You sure like to throw new parts in. Even so its great to see people doing AC work on their own... most people won't go near it because of all the stupid laws. I'm not willing to pay extortion-like prices to an AC shop so I've tinkered with it as well in the past.

Remember when recharging that you aren't shooting for an arbitrary psi number but the correct compressor duty cycle at a given ambient temp.

Keep us updated.

 

[opie74]

Yes, OCD.

 

[opie74]

Oil capacity question....

Best I can gather is the compressor takes 3 ounces, but if I am replacing other items, I need to add more oil to the compressor. Drier calls for .71 ounces and condensor calls for about 1.7 ounces according to the FSM. Should I just pour out whats in the new compressor and put in 6 ounces of oil total?

I did have the refrigerant pulled from the system today and 1.87 pounds was removed. Sticker on the core support says a max of 1.54 pounds.

 

[Singtoe]

Oil capacity question....

Best I can gather is the compressor takes 3 ounces, but if I am replacing other items, I need to add more oil to the compressor. Drier calls for .71 ounces and condensor calls for about 1.7 ounces according to the FSM. Should I just pour out whats in the new compressor and put in 6 ounces of oil total?

I did have the refrigerant pulled from the system today and 1.87 pounds was removed. Sticker on the core support says a max of 1.54 pounds.

Read the directions on the new compressor. It will usually tell you how much oil was installed in the compressor.

If it says, "Filled to factory Specs" then it should have 3 oz in it. Just add 3 more to the receiver drier.

 

[opie74]

Read the directions on the new compressor. It will usually tell you how much oil was installed in the compressor.

If it says, "Filled to factory Specs" then it should have 3 oz in it. Just add 3 more to the receiver drier.

Instructions say to dump the oil out of the old compressor and compare to what comes out of the new one. There is no mention of how much should be in the new one and with the system purged now, can I really expect to get the proper amount of oil out of the old compressor?

The instructions do state that re-manufactured compressors are shipped with the proper amount and type of oil.

 

[Singtoe]

Can't just dump oil out of the compressor. It has an inner chamber is seperarated by reed valves so taking the caps off and turning it over won't drain all the oil out.

There is a screw to the middle chamber but if you don't have a replacement seal for it, I wouldn't open it up.

PS. That is some stupid instructions " take the oil out and compare it to the new oil"

You could have more of the ac oil in the rest of the ac system or You could have lost oil during the evacuation process.

There is no way a of knowing how much oil was in the old compressor.

 

[Rangeroad]

I just finished adding r134a and am at 40psi...not ice-cold, but I do not want to overcharge it.

I wanted to check on the oil and add if neccesary, but can't find the info. on this.

Its a 1997 and the original PO did not do any oil top-ups to the A/C system.

 

[opie74]

Can't just dump oil out of the compressor. It has an inner chamber is seperarated by reed valves so taking the caps off and turning it over won't drain all the oil out.

There is a screw to the middle chamber but if you don't have a replacement seal for it, I wouldn't open it up.

PS. That is some stupid instructions " take the oil out and compare it to the new oil"

You could have more of the ac oil in the rest of the ac system or You could have lost oil during the evacuation process.

There is no way a of knowing how much oil was in the old compressor.

Yep, and I can not find the information anywhere. I did find a site that lists the model of our compressors and it states they take between 6 and 8 ounces of oil. According to the FSM, there are specific amount to be added to other replaced components so I am wondering if all the amounts added to the various components should add up to the total.....

 

[opie74]

Allright... I got everything done today. Took me most of the day, part of the slowness was the kids running around and a movie run late in the afternoon.

Anyway, everything went pretty smoothly. I replaced the compressor, the expansion valve, condenser and drier. I did not get any pics cause it was hot and I was dirty. I did not want to take the time to wash hands to take a picture.

When I had the refrigerant pulled out, there was 1.87 pounds in it. A wee bit overcharged. Weird thing is what was in there is fluorescent green. Now its clear like it is supposed to be. No big surprises and the hardest part was pulling the cooling unit from under the dash, and even that was not difficult. I bought 2 12 ounce cans of Dupont Suva 134a and both cans went in for a total of 24 ounces. The high side of the recommended charge is 1.5 pounds and both cans puts me right there. I should have stopped before dumping the entire second can in, but something I did not expect was happening. I could not get the bubbles in the sight glass to go way. So after dumping all 24 ounces in, I read in the FSM that on very hot days, even a correct charge can show bubbles in the sight glass. It was 92 here today and I got the duct temp down to 58. Should be colder but it was hot and humid today. With idle at around 1500, low side is at 35psi and the high side goes between 180 and 250.

Aside from the initial cost of the equipment necessary to perform this work, I would encourage anyone else to work on their own AC.

 

[Singtoe]

Did you vacuum down the system? and for how long.


BTW. The florescent green was a dye that was installed sometime before you got the 4runner and some time after it was sold from the dealer. The use of a UV light would make finding leaks easy with the dye in the system.