diff --git a/homeassistant/components/modbus/__init__.py b/homeassistant/components/modbus/__init__.py
index 36e841f7859..0ceb1a2523f 100644
--- a/homeassistant/components/modbus/__init__.py
+++ b/homeassistant/components/modbus/__init__.py
@@ -241,8 +241,8 @@ CLIMATE_SCHEMA = vol.All(
         {
             vol.Required(CONF_TARGET_TEMP): cv.positive_int,
             vol.Optional(CONF_TARGET_TEMP_WRITE_REGISTERS, default=False): cv.boolean,
-            vol.Optional(CONF_MAX_TEMP, default=35): cv.positive_float,
-            vol.Optional(CONF_MIN_TEMP, default=5): cv.positive_float,
+            vol.Optional(CONF_MAX_TEMP, default=35): vol.Coerce(float),
+            vol.Optional(CONF_MIN_TEMP, default=5): vol.Coerce(float),
             vol.Optional(CONF_STEP, default=0.5): vol.Coerce(float),
             vol.Optional(CONF_TEMPERATURE_UNIT, default=DEFAULT_TEMP_UNIT): cv.string,
             vol.Optional(CONF_HVAC_ONOFF_REGISTER): cv.positive_int,
diff --git a/tests/components/modbus/test_climate.py b/tests/components/modbus/test_climate.py
index 3ff9aa37bcf..b885e6452d8 100644
--- a/tests/components/modbus/test_climate.py
+++ b/tests/components/modbus/test_climate.py
@@ -42,6 +42,8 @@ from homeassistant.components.modbus.const import (
     CONF_HVAC_MODE_REGISTER,
     CONF_HVAC_MODE_VALUES,
     CONF_HVAC_ONOFF_REGISTER,
+    CONF_MAX_TEMP,
+    CONF_MIN_TEMP,
     CONF_TARGET_TEMP,
     CONF_TARGET_TEMP_WRITE_REGISTERS,
     CONF_WRITE_REGISTERS,
@@ -170,6 +172,30 @@ ENTITY_ID = f"{CLIMATE_DOMAIN}.{TEST_ENTITY_NAME}".replace(" ", "_")
                 }
             ],
         },
+        {
+            CONF_CLIMATES: [
+                {
+                    CONF_NAME: TEST_ENTITY_NAME,
+                    CONF_TARGET_TEMP: 117,
+                    CONF_ADDRESS: 117,
+                    CONF_SLAVE: 10,
+                    CONF_MIN_TEMP: 23,
+                    CONF_MAX_TEMP: 57,
+                }
+            ],
+        },
+        {
+            CONF_CLIMATES: [
+                {
+                    CONF_NAME: TEST_ENTITY_NAME,
+                    CONF_TARGET_TEMP: 117,
+                    CONF_ADDRESS: 117,
+                    CONF_SLAVE: 10,
+                    CONF_MIN_TEMP: -57,
+                    CONF_MAX_TEMP: -23,
+                }
+            ],
+        },
     ],
 )
 async def test_config_climate(hass: HomeAssistant, mock_modbus) -> None: