Question about 2000 Volvo S80
Volvo S80 Yr. 2000 2.9 Volvo S80 2000 2.9
I am trying to help a mechanic friend with the following problems. This is not my car so I do not know much about.
1)Temperature gauge wont work. Changed gauge and still wont work. Changed sensor at water outlet and check cooling system. Wont overheat. O.K.
2)A/C clutch will not engage. It activates only if giving ground to the cycle switch at the condenser area.
No other known history of problems.
Check the wires on the coolant temp for continuity the A/c system may be empty it has to full to engage the compressor
Posted on Dec 15, 2009
As for the Coolant temperature, disconnect the wire harness from the sensor and see if there is any moments on the gauge and then ground it and see if there is any readings. If there is no readings then there is no power to the Gauge on the dash or there is a break on the ground wire from the sensor to the gauge. Common cause is a bad ground from the gauge to the gauge, most likely from the sensor. As for the A/C compressor not working, you may be low on R134a in the system which will not activate the Compressor to keep it from burning out. When you grounding out the a/c line pressure switch the compressor clutch will activate which is a good thing to know that it's not your compressor. The a/c line pressure with out the engine running should be around 100 PSI and with the a/c running the line pressure should be 200 on the high side and 30 on the low side
The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low.
Most systems will have a low pressure cut off switch that turns the system off at approximately 20 psi. The compressor will not function again until the pressure reaches approximately 45 psi. So, In most cases, you will need a static pressure of at least 45 psi before you begin to see the compressor operate.
You can begin testing with only 45 psi. You won't get any cold air, but you should should start to see some compressor engagement. As soon as the compressor engages, it will cycle off rather quickly when the suction side of the compressor draws the pressure on the low side below 20 psi.. You will see the low side gauge at 45 psi, drop quickly to 20 psi, at which point the compressor will cycle off. Then the low side gauge will climb back up to 45 psi as the high and low side equalize. At this point, he compressor will kick back on and the cycle will repeat itself. This is called short cycling. This rapid cycling of the compressor is a good indication that the system is low of refrigerant.
System design, blower speed, mode setting, refrigerant type, all cause variance in high and low side pressure. For this reason we simply can't say 30 on the low side and 200 on the high side. Though I might add, that's about where you'll usually end up. The reason 30 psi on the low side is just about right is because that translates into an evaporator temperature somewhere around the freezing point of water. The low side pressure translates into evaporator temperature. Since moisture collects on the evaporator, we would like to keep the evaporator temperature slightly above the freezing point. R134a low side pressure will be be slightly lower (27 PSI) at this temperature. Again, refrigerant type is one of those variables we have to consider.
Good luck and hope this helps. Keep me posted and if the A/C pressure is correct in the system, then you have a faulty A/C line pressure switch.
Posted on Dec 15, 2009
The AC is a gas problem it has low gas pressure so it will not engage the pump ,evan if you ground the switch to force the pump on it might blow a bit of cold but the gas volume by weight is what makes it cut in so a simple gas recharge will cure this.To cure the temp reading i think you may have to fit a new panel complete ,remember that this is a volvo and ford own volvo so it is no doubt the same unit as a focus ,these have the same problem with the gauges ,best advice here is fit an add on temp gauge it will be cheaper in the long run
Posted on Dec 11, 2009
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Posted on Jan 02, 2017
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