Working on a 2013 Honda fit that has no power to the ac compressor . Initially fuses were blown and I replaced them . Relay is getting power. Relay tested good . Tried to use a scan tool to command the ac compressor on and compress clicks (key on engine off) also tried jumping the pressure switch but no luck. Replaced the ac button as well. Tested the thermal sensor has continuity. Any help is greatly appreciated

 

If the compressor clicks when commanded, it's getting power. I assume you mean the compressor relay clicks.

Blown fuses usually indicate a short, which can pop wires depending on the situation. Test continuity to ground on the compressor terminal to make sure the clutch coil is still in tact. Then work back from there testing continuity of the wires at the connector/socket terminals.

 

With the three pin connector disconnected , there should be power to the red wire but in this case it's not. So I'm thinking whatever the issue is must be before the compressor.

 

Above diagram shows the red wire is a sense pin going to the body control module (dash fuse box). I suppose there aught to be a pull-up voltage from the BCM since it's sensing a ground-signal. Does the pull-up voltage (could be 12V or 5V or 3.3V or even something pulsed) appear when the engine is running? If not, it sounds like you've got a short to ground on the red wire (though A/C should be running constantly in that case) or a bad BCM. Does the A/C demand signal update properly on your scan tool?

 

With the scan tool , key on engine off I can command the ac clutch . The ac clutch clicks on. When checking voltage on red center wire with voltmeter , there's about 11 volts . (Not enough to engage clutch ) . I can jump the red wire on compressor also with power probe and compressor will click . I have already tried jumping the pressure switch no luck. Also the ac fans are not working

 

What wiring diagram are you working from? I ask because the wire colors on the diagram I found are conflicting with what you're saying.

You're sure it's the compressor clutch plates clicking together, and not just the relay? The scan tool lets you command the compressor relay to turn on. Same goes for the fans. The fuses, wiring, relays and such need to be in working order for the ECM command to do anything. If you can plug the compressor in, tell the ECM to turn the clutch on and the clutch plates snap together, there's nothing wrong (electrically) with the compressor clutch or its wiring.

The BCM and ECM are acting as middle-men in controlling the A/C system. The BCM (part of the dash fuse box) is receiving the A/C-demand signal (ground to activate) after it has passed through all the switches. The BCM reports that over the CAN bus, the ECM responds by activating the fan and compressor relays, boosts the idle and whatever else, as needed to get the evaporator in the right temperature range (the ECM has a sensor for measuring that).

Current (amps) makes magnetism, not voltage. Voltage is needed to push the current, but is a very poor indicator of what's actually happening with the clutch. 8 or 9 volts might be enough to pull the clutch in, but would indicate something else in the circuit (damaged wire, worn relay contacts) is causing a voltage drop that shouldn't be there. You need to measure the voltage across the device in question (clutch coil) with the circuit connected and powered up. That usually requires a jumper harness for a connector, back-pinning a connector or (less desirably) insulation-piercing probe(s). If you're seeing 11 volts in that situation, that's fine... Not optimal, but functional.

Sounds like the clutch coil is fine. Do the cooling fans come on to cool the engine? If the fans come on when the engine is hot, there's nothing wrong there electrically - The ECM hasn't commanded them to turn on, probably because it isn't getting the message to turn on the A/C.

 

I'm using Mitchell pro demand diagram. Looks very similar to the one you shared . When I command the ac clutch with scanner I confirmed it's the clutch engaging and not the relay. The cooling fan cycles normally . However condenser fan does not ..I tested the condensor fan by applying power with probe and jumping relay and it works.
It seemed like when I pressed the ac button, the compressor won't engage so I removed the ac button and tested it . I noticed I only had continuity on two of the pin when the switch was slightly pushed . Bought a brand new switch and did the same test and confirmed when the button is pressed the first two pins have continuity. Since the ac clutch is engaging through the scanner, I thaught the system is okay and its the switch. After installing new switch still no luck.
The red wire in center is the one I was referring to . It's circled in the picture .

 

What about the a/c pressure switch? If I recall it is connected to the condenser (?) and will not allow the A/C to turn on if the pressure is too low. Maybe the charge is too low or this switch is faulty? Since you are handy you could check to see if the switch sees the correct voltage. I could see in my service manual if there is more info on how to diagnose the pressure switch.

 

I checked the pressure multiple times and it's good. Also I tried jumping the connector but no luck

 

I back tracked my steps and carefully check each wire ... When I did continuity on ac compressor harness I noticed continuity was not present. The thermal protector's harness had a cut that was hardly noticeable bc the harness is inside a sleeve. Reconnected the harness plugged in the compressor and it works now. Appreciate the help

 

congrats! Yea there’s that pesky metal retaining clip for the wires and I’ve seen it cause some fretting damage. Might be the culprit.

 

Glad to hear you sorted it.

I'm going to type out the A/C demand side of the circuit in case someone else comes along with a similar problem. Follow along if the diagram looks like meaningless tech-spaghetti. Note the diagram is from the '09-12 service manual. I assume the 2013 is the same, but don't have a manual that specifically says so.

As I said above, the electrical portion of the demand signal ends with the MICU (Multiplex Integrated Control Unit, aka Body Control Module) in the under-dash fuse box. Looking at the diagram I posted, it's a small-ish box just down and left of center. The MICU is looking for a connection to ground to indicate a request for A/C, or an open-circuit (open switch contacts) to indicate no demand.
Since it's a ground-activated signal, I'll start at the ground "source": the ground point for the heater fan speed switch, at G502 (the label for the specific ground point on the car body), found along the bottom of the diagram just right of center. If you follow the wire up on the diagram, it connects to the common terminal of the fan speed switch, which dead-ends if the fan is set to "off", or gets sent out to one of the three fan resistors pins (the resistors limit the fan speed) or directly to the fan (the highest setting) depending on the switch position. Looking at the switch symbol, it also has a curved bar across the four "on" positions. The bar is an electrical contact (making it a double-pole switch if you're familiar with switch terminology) which provides ground when the fan is on, or open-circuit when the fan is off. That bar is the start of the the A/C-demand signal, only enabling the A/C system if the fan is on.
Following the demand signal line from the fan switch bar, it exits the box for the "Heater-A/C Control Panel". The relevant connector terminal number is next to the fan switch box instead of the control panel box because the switch has its own connector - the switch is mounted to the control panel but is otherwise independent. The solid white (wht) demand wire splits two ways just under the control panel box, as there's two ways to activate the A/C system. One side of the split goes right to the push-button A/C switch, the other goes straight up back into the control panel, connecting to the common terminal of the Mode Control Switch.
The Fit has manually-operated mode selection (mode being the knob that selects air going to your face, feet or windshield) - when you turn the knob, you're moving a cable that moves air-control flaps in the air handler. Meaning the A/C demand contacts are the only electrical connections on the Mode Control Switch. Looking at the Mode switch symbol, there that bar thing again. The switch passes the demand signal along in the windshield+feet or windshield-only positions, out of the control panel on the blue wire.
The right branch of the earlier white wire goes to the push button A/C switch. Again, the A/C switch has its own connector - this is common in cars where A/C is optional equipment. In the switch symbol, there's two sets of contacts, linked by a dotted line which indicates they move together but are not electrically connected. That said, the incoming A/C demand signal splits and connects to one terminal of each set of contacts. The right switch contacts operate the indicator light. The light gets power on one terminal when the ignition is on (IG2, meaning power with the ignition "ON" but not in "ACC" or "START" positions) as long as fuse no. 10 is is good. The light gets ground on its other terminal (making the indicator illuminate) if the A/C switch is pressed and the fan is on. Meaning the A/C switch indicator doesn't actually tell you much about the A/C system's functionality. The left switch contacts pass the A/C demand signal along out of the switch on a blue wire, which then joins the blue wire from the Mode Control Switch and continues on to the A/C Pressure Switch.
The two panel switches (A/C button and mode control) are said to be wired in "parallel" because they both share source and load wires. Switches in parallel have a logical "OR" function. Meaning if either the A/C button is pressed OR the mode control is set to one of the windshield positions, the demand signal gets passed along in the chain. If you're old-school (or watching your MPGs) and want full control over the air conditioning, disconnecting one or both of the Mode Control Switch wires will make the A/C come on only when the button is pressed.
Continuing on, the blue wire passes the demand signal along to the A/C Pressure Switch. The pressure switch's job is to protect the system in the event of refrigerant loss (a leak) or over-pressure (a clogged expansion valve). It passes the demand signal along (closed switch contacts) as long as the pressure on the high-side A/C line is between 196 kPA (2.00 kgf/cm², 28.4 psi) and 3,138 kPa (32.00 kgf/cm², 455.1 psi). You would need an A/C gauge set connected to the high-side (smaller) service port to check the pressure.
The demand signal exits the pressure switch on a white wire which runs to the thermal protector on the compressor. As it's name suggests, the thermal protector protects the compressor from overheating. The protector passes the signal along (closed contacts) until it exceeds 125±3°C (~257±5°F) at which point it will go open-circuit until its temperature drops to 110±6°C (230±11°F). The different opening and closing temperatures is an example of hysteresis, which keeps the system from rapidly cycling on and off. Note the diagram doesn't show wire colors for the sub-harness on the A/C compressor itself, only the car-side of the 3-pin compressor connector.
After the thermal protector, the demand signal pops out of the compressor connector on a red wire which runs all the way back to the MICU/BCM in the dash fuse box. As I said earlier, the MICU/BCM looks for a ground connection there. If it sees ground, it sends a message over the B-CAN bus to the gauge module, which passes it along the ECM on the F-CAN bus.
The ECM has an evaporator (the cold part) temperature sensor in addition to all its engine sensors which it uses to decide whether or not to turn on the A/C compressor. The ECM has exclusive control over the compressor, radiator fan, and condenser fan relays. If either of the fans are operating normally, but don't come on when the A/C button is pressed, look for an issue in the above demand circuit.