Do the A/C pipes going in through the fire wall get cold ( icy) ? Temp blend dood actuator possibly .Does it have A/C system in the back as well ? Auxiliary - does it get cold ?
Air Temperature Actuator
The air temperature actuator is a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volt linear-ramped signal to command the actuator movement. The 0 and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between 0-12 volts correspond to the positions between the limits.
When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed.
Have you hooked up manifold gauge's to check pressures ?
Yes my low side comes out from the expansion valve cool, but not icy. I checked the manifold pressures and they are: low side - 35 psi, high side, 115-125 psi. The needles hardly move as the a/c runs. I did some freeway driving today and got cold air to blow through the vents, but it would cycle between warm and cold air. I'm starting to think I have a bad expansion valve for the front. The rear ac blows a consistent cold air through the vents.
I'm looking into replacing the front expansion valve as well as the receiver drier. I'll be checking the condenser for cold spots soon in case there's a blockage there. I doubt it however seeing as the rear a/c seems to work alright. I don't know what manifold pressures are good so I'll wait to hear back.
At what temp ? out side temp.
About 70 degrees
low side looks good , high side is low .
Table 1: A/C Performance Table
Table 2: A/C Performance Table - with Rear A/C
Test Description
This test measures the operating efficiency of the A/C system under the following conditions:
• The current ambient air temperature
• The current relative humidity
• The high side pressure of the A/C system
• The low side pressure of the A/C system
• The temperature of the air being discharged into the passenger compartment
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the A/C system has at least the minimum refrigerant charge required to operate the system without damage.
This step measures the performance of the A/C system.
This step is to allow for vehicle variations as well as high ambient temperatures.
Step
Action
Values
Yes
No
Important:
• The ambient air temperature must be at least 16°C (60°F) .
• Do not induce additional air flow across the front of the vehicle during the test.
• If you were sent here from a DTC diagnostic table, clear the DTC upon completion of this test.
1
Park the vehicle inside or in the shade.
Open the windows in order to ventilate the interior of the vehicle.
If the A/C system was operating, allow the A/C system to equalize for about 2 minutes.
Turn OFF the ignition.
Install the J 43600 ACR 2000 Air Conditioning Service Center.
Record the ambient air temperature displayed on the J 43600 .
Record the low and high side STATIC pressure readings.
Are both the low side and high side pressures within the specified value?
Greater than 16°C (60°F) - 345 kPa (50 psi)
Greater than 24°C (75°F) - 483 kPa (70 psi)
Greater than 33°C (90°F) - 690 kPa (100 psi)
Go to Step 2
Go to Leak Testing
2
Important: Record the relative humidity and the ambient air temperature at the time of the test.
Close the vehicle doors and windows.
Open the drivers door window 12.7-15.2 cm (5-6 in).
Select the following HVAC control settings:
• A/C setting
• Recirculation mode
• Maximum blower speed
• Panel mode
• Coldest temperature setting
• Open all panel air outlets
• If equipped, maximum auxiliary blower speed
• If equipped, coldest auxiliary temperature setting
• If equipped, open all auxiliary air outlets
Install the temperature probes of J 43600 in the left and right center panel air outlets.
Apply the parking brake.
Place the transaxle in PARK.
Start the engine.
Operate the A/C system for 5 minutes.
Inspect the A/C components for abnormal frost areas and for unusual noises.
Important: Press the RESET button, before using the print function of J 43600 .
Print the following information:
• The panel outlet air temperature
• The low-side pressure
• The high-side pressure
Compare the printed information to the table below.
Does all the data recorded fall within the specified ranges of the table below?
--
Go to Step 8
Go to Step 3
3
If the pressures and temperature recorded do not fall within the specified ranges, perform the following procedure:
Continue to operate the A/C system for an additional 5 minutes.
RESET J 43600 and record the pressures and temperature again.
Compare the new results to the table below.
Does all the data recorded fall within the specified ranges of the table below?
--
Go to Step 8
Go to Step 4
4
Do the pressures fall within the specified ranges, but the panel outlet temperature does not?
--
Go to Air Conditioning (A/C) Diagnostics - Pressure Zone A
Go to Step 5
5
Is the low side pressure greater than the specified range, but the high side pressure is within or less than the specified range?
--
Go to Air Conditioning (A/C) Diagnostics - Pressure Zone B
Go to Step 6
6
Are the low and high side pressures both greater than the specified ranges?
--
Go to Air Conditioning (A/C) Diagnostics - Pressure Zone C
Go to Step 7
7
Is the high side pressure greater than the specified range, but the low side pressure is within or less than the specified range?
--
Go to Air Conditioning (A/C) Diagnostics - Pressure Zone D
Go to Step 8
8
Operate the system in order to verify the test results.
Did you find the same results?
--
System OK
Go to Symptoms - HVAC Systems - Manual
A/C System Pressure -- Zone Classification
A/C Performance Table Ambient Air Temperature
Relative Humidity
Service Port Pressure
Maximum Left Center Discharge Air Temperature
Low Side
High Side
13-18°C (55-65°F)
0-100%
197-225 kPa (29-33 psi)
1100-1230 kPa (160-178 psi)
9°C (48°F)
19-23°C (66-75°F)
Below 40%
191-228 kPa (28-33 psi)
1060-1230 kPa (154-178 psi)
10°C (50°F)
Above 40%
202-246 kPa (29-36 psi)
1100-1370 kPa (160-199 psi)
12°C (54°F)
24-29°C (76-85°F)
Below 35%
194-230 kPa (28-33 psi)
1130-1220 kPa (164-177 psi)
11°C (52°F)
35-60%
198-246 kPa (29-36 psi)
1090-1320 kPa (158-191 psi)
12°C (54°F)
Above 60%
236-311 kPa (34-45 psi)
1140-1580 kPa (165-229 psi)
15°C (59°F)
30-35°C (86-95°F)
Below 30%
208-256 kPa (30-37 psi)
1230-1370 kPa (178-199 psi)
14°C (57°F)
30-50%
215-284 kPa (31-41 psi)
1180-1540 kPa (171-223 psi)
16°C (61°F)
Above 50%
236-311 kPa (34-45 psi)
1290-1750 kPa (187-254 psi)
18°C (64°F)
36-40°C (96-105°F)
Below 20%
235-298 kPa (34-43 psi)
1340-1600 kPa (194-232 psi)
17°C (63°F)
20-40%
246-315 kPa (36-46 psi)
1340-1700 kPa (194-247 psi)
18°C (64°F)
Above 40%
260-348 kPa (38-51 psi)
1410-1940 kPa (204-281 psi)
21°C (70°F)
41-46°C (106-115°F)
Below 20%
266-339 kPa (39-49 psi)
1550-1820 kPa (225-264 psi)
21°C (70°F)
Above 20%
280-369 kPa (41-54 psi)
1530-2000 kPa (222-290 psi)
23°C (73°F)
47-49°C (116-120°F)
Below 30%
304-378 kPa (44-55 psi)
1870-2020 kPa (271-293 psi)
24°C (75°F)
Right thanks very much. I will try slowly adding refrigerant while keeping an eye on the gauges to see how the system reacts.
https://www.youtube.com/watch?v=UW1GDiOa...
watch this video
Watch this video , show's how to tell if TXV is going bad .
https://www.youtube.com/watch?v=sOPn8BQB...
Thank you very much for the great videos!
So I was able to get the manifold gauges hooked up again to do some more tests. The van had sat so the engine was cold. The outside temp was 70 once again. The low side dropped to 20, and the high side climbed up to 200 psi while the compressor ran. Once it stopped, the low side climbed and held at 25 psi, and the high side over 10 seconds fell to 100 psi and held there. Every time the compressor kicked on, the high would instantly climb to 200, and then fall back to 100 psi after it shut off. I added a 12 oz. can of refrigerant while carefully monitoring the gauges. I got the low side up to about 30 psi, and the high side 125 psi. While the compressor runs, it now spikes up to about 250 psi before falling back to 125 psi. That kind of pressure seems very excessive. Is that just a symptom of the compressor running?
What's the humidity like ? With the gauges hooked up - engine not running the high an low side should equalize to around 100 to 120 psi. . this would signify that enough ref. was in the system an no blockage's in the system .
The system equalizes to about 70 psi. I live in northern Utah, and the weather has been particularly dry lately. I'm not sure how long it takes to equalize. I'll have to test that.
Shouldn't take long at all to equalize , a few min.
If it does equalize , wouldn't think a problem with TXV - Maybe the temp. blend door actuator .
Alright I'll check it out when I get the chance! Thanks!
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SOURCE: No cold air w/air conditioner on for a 2004 GMC Envoy.
Can't go by the pressure. Ck the large lone coming out of firewall, should be col. Small line at ac condensor in front of radiator should be hot.
Static pressure on high side probably 80psI Running 30 on the low side and 1130. will vary depending on oiutside temp Hope this hekoped
SOURCE: air conditioning
There are many possible reasons for this event and if the compressor is engaging and you dont have the proper training and equipment you need a professional diagnosis in person. You may have under or overcharged refrigerant level. when did it work correctly last? Has there been an attempt to charge the system? If so what were the gauge readings ? Are your cooling fans on your radiator and condensor running? It can be as simple as a servo relay on a gate or door in the plenum directing the air in the wrong direction. Is there condensation dripping from out from under the cowl area? Are any of the a/c lines under the hood sweaty looking? Or it may have a cloged expansion valve or bad compressor. Auto a/c not repaired correctly can and usually does cost more and is frusterating as well as dangerous if not done by a competent trained or knowledgeable person. good luck
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