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Hey guys,
99 Vert, I don't use the AC a lot but want to get this working.
This year when hit the ac button it flashes a few times and then shuts off.
1) No codes
2) fuse 26 is good and I get power there when ignition is on.
3) swapped relays with horn.
4) Attached my gauges to high & low side and get about 15 on both when car is off and does not change when car is running with air on.
5) Outside temp is 80 degrees and I adjusted to coolest setting 60 with fan on high
I even tried disconnecting the battery and tried to charge.
What can cause the low side not to suck in 134 to get the compressor to turn on? or am I missing something?
The static pressure (car off and pressures equalized ) with R134 should be approximately ambient temp for the compressor to at least run…15 vs 80 is not good…you are low on Freon…you can jump pins 87 and 30 (shown in white) on the relay to get the compressor to operate and draw the Freon in !!
…and remember to much Freon is as bad as not enough !!…if you are unsure of how much Freon is in the system take it to an AC specialist so that the proper amount can be added !!
This is awesome, thank you C5 Diag.
I searched for hours for the information you just posted.
I will get back on this next weekend, as a last resort, I took off the connection to the AC compressor to clean and inspect all connections, I cant get this back on from up top, something is not right and will have to get the car it in the air to reattach this.
I did not want to force it and bend the two pins so I will respond to this next weekend.
If this works, I owe you some beer if you ever get to Long Island again.
You’re welcome !!…if you jump 87 and 30 with key on and if the compressor clutch engages the load side of the relay is OK…keep us updated if you need to diagnose it further….don’t think I’ll be making it to the NYC area anytime soon…loving it down here in “Corvette Central” !!
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
Originally Posted by C5 Diag
You’re welcome !!…if you jump 87 and 30 with key on and if the compressor clutch engages the load side of the relay is OK…keep us updated if you need to diagnose it further….don’t think I’ll be making it to the NYC area anytime soon…loving it down here in “Corvette Central” !!
Is there a sight glass anywhere in the C5 AC system? I think mine is not as cold as it used to be and would like to check the refrigerant level.
If there isn't a sight glass, what procedure can I follow to determine whether I have enough refrigerant in there? Is there one in the manual?
Is there a sight glass anywhere in the C5 AC system? I think mine is not as cold as it used to be and would like to check the refrigerant level.
If there isn't a sight glass, what procedure can I follow to determine whether I have enough refrigerant in there? Is there one in the manual?
No sightglass…your best action is to see if you may have a leak first if it’s not as cold as it used to be and then evacuate the system and add the correct amount of Freon…let an AC shop do it unless you have the proper equipment…too much refrigerant is just as bad as not enough…don’t guess !!
No sightglass…your best action is to see if you may have a leak first if it’s not as cold as it used to be and then evacuate the system and add the correct amount of Freon…let an AC shop do it…too much refrigerant is just as bad as not enough…don’t guess !!
Oh, I know.
That's what I was afraid you were going to say.
I miss the "good old days" of the sight glass. Thanks
No sightglass…your best action is to see if you may have a leak first if it’s not as cold as it used to be and then evacuate the system and add the correct amount of Freon…let an AC shop do it unless you have the proper equipment…too much refrigerant is just as bad as not enough…don’t guess !!
Can't you use the ambient temperature and a chart to add the correct amount of refrigerant? Without a scale, that's the only way to get the right amount.
Can't you use the ambient temperature and a chart to add the correct amount of refrigerant? Without a scale, that's the only way to get the right amount.
Like a super heat or supercool. I suppose I can, and I know how and have the tools. I've only done it on residential systems, though.
I don't know whether the expansion valve on a 2002 C5 is a fixed orifice or a thermostatically controlled one. Any idea?
Can't you use the ambient temperature and a chart to add the correct amount of refrigerant? Without a scale, that's the only way to get the right amount.
No, you only use ambient temperature/pressure relationship to determine if you have at least enough Freon to turn on the compressor. You would need a scale to determine accurately how much Freon to add.
No, you only use ambient temperature/pressure relationship to determine if you have at least enough Freon to turn on the compressor. You would need a scale to determine accurately how much Freon to add.
But that doesn't tell me how much is already in there - just that there is some in there.
Like a super heat or supercool. I suppose I can, and I know how and have the tools. I've only done it on residential systems, though.
I don't know whether the expansion valve on a 2002 C5 is a fixed orifice or a thermostatically controlled one. Any idea?
No, you only use ambient temperature/pressure relationship to determine if you have at least enough Freon to turn on the compressor. You would need a scale to determine accurately how much Freon to add.
Looks like I need to buy a scale. Thanks for the input.
Well if you want a project rather than evacuate and charge, you can come quite close by basically doing a charge determination. You will need to measure the low side evaporator out temperature and the low side evaporator out pressure. A thermocouple clamped to the inlet pipe of the accumulator dehydrator and a pressure reading at the low side service port will be close enough. You will also need an R134 saturated temperature and pressure table. Lastly, you will need to meter in the R 134a to the service port. You dont have to do this but it is good to monitor the high side pressure too.
Here is what you do on a hot day.
Hook up your temperature and pressure measuring instruments.
a/c on high blower and outside air
Drive at a steady speed, say 30mph and hold it there.
Assuming you are low on charge, you will see your low side pressure around 30psi but your evap out temperature quite high, say 70 degrees.
Slowly add charge in eighth pound increment and watch the evap out temp drop. When the evapout temp has stabilized, check the r134a chart and see what the saturation pressure is for that temp (or vice versa, for the low side pressure, what is the saturation temperature).
Keep adding in eight pound increments until you evapout temperature is at the saturation pressure (or vice versa).
then add one eighth pound as charge reserve.
Orifice tube systems do not control superheat of the evaporator out. They may have some liquid refrigerant coming out which is one reason for an accumulator dehydrator. It captures that liquid so that only gas goes to the compressor.
I am not really suggesting you do this because its much easier to evacuate and charge. I am just saying that it is possible to figure out how much charge needs to be added and to know when you have added enough.
Personally, what I do is much cruder. I know about what discharge air temperature my system should deliver, I know my suction line needs to be cold, and I keep an eye on my gages as I add charge with the car idling on my driveway.
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AC wont take charge
But I agree, at least from October to May!!